Prebuilt PC is the way to go, don't start off building your own. Build your next one yourself 8 years from now or whatever. Or just slowly swap parts.

I got my households last 3 machines built by CyberPower PC, I dont keep up with everything so I can't say whether it's the best option, but it all worked out great for me. I could have built, but I had to get prebuilt because of some part scarcity at the time.

Before you decide on a PC tower budget, make sure you account for decent peripherals. You dont need crazy shit, but getting to that nice B-tier level of quality will get you 98% of the value honestly.

• Mid range Logitech gaming mouse. FUCK Razer, the hardware is good but the software is outlandishly broken, avoid. Corsair can be great for that mid range but they have a high defective rate. Logitech.
• BIG mousepad, so you can set your mouse to a somewhat low/slow setting. That will let you control it better.
• Mid-range mechanical keyboard. You might want one without the numpad, and go buy a 10 dollar separate numpad keyboard for the 5 times you're gonna use it this year. Better for your arms and gives you more space to swing that mouse.
• if you are using the computer nearby someone, get the quieter mechanical keys!! It will say "red switches" "blue switches" etc on the keyboard's sales listing, and you gotta Google what that means. If theres nobody around to get mad at your noisy keyboard, get "tactile" switches like Blue (loud) or Brown(less loud). The "linear" switches can be nice for some games, but you'll mistype a lot. They're hard to type on for most people. Very sensitive.
• Spend like 200-300 bucks on a monitor. That's not fancy but is likely quite good. Look for response times in milliseconds, make sure it's under 10 or so milliseconds. 5ms are actually pretty common. 1080p is fine, or get a widescreen but not like ultrawide. See this monitor?I literally have never used this monitor, I just did a Google search, but it's probably fantastic for what you need. Honestly, just Google "mid range gaming monitors". Any monitor for gaming will very likely be good and not fuck you over, while a non-gaming monitor might fuck you over by being really slow or whatever.
• check if the monitor has built in speakers. If not you obviously need speakers no question. BUT if you do cheap out and not buy speakers, you gotta gotta gotta get headphones (and probably an audio cable extension). Headphones are better for gaming.
• Wireless bluetooth headphones tend to not work while they're being charged, for some fucking reason, so I avoid them. I never fucking remember to charge them and then I'm fucked when I want to use them. Up to you.
• Gaming headphones often have mics. The mics slightly suck ass, and I use a separate microphone. But honestly... Setting up multi-device computer audio is such a fucking hassle, it's so fucking annoying, and if the software doesn't fuck you, you'll get some stupid echo or static or ambient noise etc... just use the stupid shitty headset mic. It's fine. Make sure to test it with someone and ask if your mic happens to be fucked up

Oh also, set up mouse your mouse sensitivity and try to get your settings saved into the "onboard memory" of the mouse so you can turn off the settings adjustment software when youre done using it. Logitech's software "GHub" lets you do that, it's worth it because even though it's not horrible like Razer, it does crash sometimes. Onboard settings will never ever fuck up.

Another sort of adjacent tip:

Google may be your class enemy, but they are your tech support friend. Most stuff you want to do will be answered by someone on the internet already.

And if the answers to your question are all vague shitty blogs, you add this to your Google search: "site:reddit.com" without the quotes. That will show you only results from :reddit-logo:. Again, that site sucks but it has a much higher success rate of actually good answers compared to the shitty blogs spamming up the rest of Google.