Imo perfectionism is a defence mechanism. A complex one that is very interesting and it can yield impressive results at times, and there's this thing that I'm going to call the perfectionist's paradox but idk if it actually has a name or whatever.

What you describe does fit with the perfectionist archetype. Throw in being highly intelligent and/or an overachiever in school and you've pretty much got all the key ingredients for ending up with perfectionism being a major source of distress in your life.

There's a few ways of tackling perfectionism but I'll try and focus on the fast fixes since that's what you're looking for.

If we presume that your perfectionism is a defence mechanism then the deeper work is to address and resolve the feeling and/or the belief that you are facing threats.

For quick ways to achieve some shifts in your degree of perfectionism, on an individual level you can try to find an activity where your enthusiasm or enjoyment outweighs your perfectionism. It might be playing a video game or cooking or arts and crafts or leaning a language. This is a very personal thing but there's likely to be at least a couple of activities where your perfectionism takes a back seat and you just find yourself just enjoying the process. Spend some time reflecting on how much enjoyment you get from one of these activities, how you don't feel the need to be perfect at it, how accidents and imperfections can contribute to the end result positively oftentimes, and how you have improved at this activity without the pressure of needing to be perfect at it.

You can wrestle with this on a cognitive or intellectual level and consider how your perfectionism inhibits your ability to practice, learn, and grow thus perfectionism becomes its own barrier to achieving perfection. Things like weighing up whether it's more important to you to learn and improve or to be perfect, because you don't get to choose both options, as well as considering how perfectionism continually raises the bar so even when you satisfy its initial standards it inevitably shifts those goalposts in response, stuff like that.

Observing kids can also be therapeutic. (Don't get the cops called on you or anything though.) But watch kids, if you get the opportunity to - they suck at everything. They still do stuff. They still enjoy stuff. They fail at things and they tend to dust themselves off and give it another shot. It's okay for you to suck at things too.

This next one can be a lot of cognitive effort but you can try setting the intent to suck at something in order to stake out some psychological territory where you don't allow perfectionism to encroach. Try something low stakes or something which is of no importance to you and how you see yourself. Mini golf is a good example of something low stakes because it's got a quaint sorta irreverent quality to it - it's hard to take it seriously or to invest ego into a round of mini golf. This can be useful for familiarising yourself with a mindset that doesn't default to perfectionism so that when you approach something that is a bit higher stakes, you can work on maintaining that same mini golf mindset. I'm sure that there are lots of other activities like this where you could practice this but this is just the first activity that springs to mind.

The next thing requires a bit more confidence so it may not be suitable for you right now but you could try playing the rejection game as a way to desensitise yourself to feeling threatened by the risk of rejection from others. Obviously this is not a license to be a creep or to harass people, respecting people's boundaries is important. But the rejection game is to ask people for things with the intent that when you get rejected, you win. This can be asking people for favours or for objects, that sort of thing. Don't ask for anything offensive or outrageous but just ask for things and get accustomed to feeling that rejection with the view that you're going to survive and it's not a big deal, in this way when you tell a joke that doesn't land it won't feel excruciating and you won't internalise it with shame and self-blame but instead you'll be more inclined to shrug your shoulders and take it as people either not getting the joke or rejecting the humour and being okay with that.

Maybe an easier entry point is to be that person who is encouraging and supportive for yourself through conscious effort and affirmations. You have to be careful not to allow your habits to turn this into a new dimension for your perfectionism to colonise though, or otherwise it can backfire.

Last of all, to get to the perfectionist's paradox idea there's this hazard in dealing with serious cases of perfectionism because you may find yourself reflexively adding an additional layer to your perfectionism by not dealing with your perfectionism "perfectly". This might look like setting the intention of doing badly at something or of practicing affirmations but slipping up and lapsing into perfectionism unconsciously only to start beating yourself up for making a mistake and not doing "well enough"; to ease off on your perfectionism, you must make your peace with the fact that you aren't going to immediately find yourself without any perfectionist thoughts or beliefs creeping in, and that's totally okay. If you're telling yourself that you need to be perfect at not being a perfectionist, surprise - your perfectionism just outflanked you completely!

With all of that said, I think it's important to approach perfectionism in a way that doesn't pose a threat to the perfectionism in you. It's a bit like a Chinese finger trap - the more you struggle against it, the tighter it seizes up on you. To get it to relax or release its grip, the right approach is one of gentleness and leaning in with curiousity and openness. Challenging the beliefs, ideas, and narrative is fine but approaching it as if you're going to eradicate your perfectionism is counterproductive imo since that will create an extra level of threat that will only serve to fuel the fire.

Edit:
I forgot but if you're open to it and if you're capable of not getting drawn into a sort of socially-driven addiction, sometimes drugs can help. Alcohol is one that is probably used the most ubiquitously in this respect but cannabis, especially high CBD stuff, can be really good for some people to ease up on their anxieties and to relax into social interactions. Just be careful not to use it as a crutch. There's also herbal options that are still drugs imo - valerian can be good and the same can be said of kava. Beta blockers such as propranolol can also be real good for this, if you can get your hands on them.

Final parting thought, what you've described and especially the selective mutism points to the possibility of autism. Just thought I'd mention it as something to consider.