One thing I don’t see any one mention in the comments, is that you should start paying attention to the “Data linked to you” section in the appstore. As an example here’s WhatsApp and Signal:
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Granted that does mean you are relying on the developer and Apple to not be deceptive, but it’s better than nothing and a good place to start.
Adding to what others here have already said, I'd definitely download Signal and see if you can get any people to move from WhatsApp/Telegram/whatever to Signal.
I don't know much about iOS apps, but you could look into more privacy focused YouTube clients, and possibly 2FA clients too (although that's a bit of a controversial topic on iOS AFAIK).
I saw you mention in another comment that you use Amazon Alexa for smart home appliances. Depending on interest in selfhosting / time / motivation to move away from Amazon, you could look into using Home Assistant instead. It even has a Lemmy community: !homeassistant@lemmy.world.
Not an app, but one thing I can recommend that is pretty much "for free" is to turn on iCloud Advanced Data Protection, that gets you end-to-end encryption for pretty much all iCloud storage (photos and so on).
Everything else I would recommend is probably not going to happen (such as deleting Discord) or of questionable benefits (such as using the web version of Discord instead of what is probably the app) :^)
The main problem is iOS sorry. Because most of privacy apps are only available on android...
