Not able to update my iphone, not connecting to my wifi, not able to use many apps in wifi, only apps work on mobile data

See the following Apple articles:

Connect to Wi-Fi on your iPhone, iPad, or iPod touch

Connect to Wi-Fi on your iPhone, iPad, or iPod touch - Apple Support

If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network

If your iPhone, iPad, or iPod touch won't connect to a Wi-Fi network - Apple Support

Recommended settings for Wi-Fi routers and access points

Recommended settings for Wi-Fi routers and access points - Apple Support

If you need help with your Wi‑Fi password

If you need help with your Wi‑Fi password - Apple Support

I can’t update my phone either, I’ve reset the network settings multiple times but my WiFi won’t turn on. I’m unable to use my personal hotspot too.

If hotspot doesn’t show it’s because your provider didn’t give you on your plan, I’ll try to help you, but first I need to know who’s your provider