Hacked iPHONE 15promax

I have a stalker so there’s that. I’m not sure how the individual obtained the information needed to hack me, but it happened.

I was on a particular hookup app and that’s where I first noticed something wasn’t right. The app is a 3rd party app connected to my gmail account that was connected to the calendar and other services that I never connected to. Then I lost control of the email account even though I had an authentication app, phone number connected, back up email address and back up codes. As far as my phone is concerned, I started noticing certain apps with permissions, my Face ID was removed, my keyboard seemed to glow a bit as I typed, kept asking for passwords, my WiFi was connection was compromised, my security key was turned off, I saw that the phone was connected to another network I’ve never seen before, other phones and bluetooth devices were also compromised and the list goes on and on.

Took the phone to Best Buy and had it wiped and reset to factory settings.

fyi: I have screenshots of all that I’m speaking of. What I want to know is what exactly do I have to do or install to keep this from ever happening again?

This is the second time. The 1st time was on an iPHONE 13promax.

Thank all of you in advance for your time and consideration. I really need your help with this.

-Beaux