Privacy features in iPhone

Are there any security features or adjustments of the like that I may be missing on my iPhone Xr? I would like to have my phone accessible to me, not everyone else but *me… There is quite a bit of different information that I’ve been reading online about this topic when I search. The fact that my phone is loaded with protocols and a vpn which enables anyone with access to those two things,, to restrict any content they’d like. And there is quite a bit of emphasis on the region in which you reside, where the “device” was purchased, different regulations, laws, standards and accessibility features, color of the phone, Multiple model numbers (some cases, on the same phone) <—— applicable RF/SAR standards, the ability to use features like scanning QR codes, RFID capabilities using small devices known as “Tags” that are able to read, write, store files on my phone. Also share, complete tasks,open apps, read any and all info on my phone whether there is a shortcut app on the phone or not. security features such as VPN, web sockets. I’m sure you see where this is going and get the point. But there must be a application or setting or some very simple way of shielding and protecting the phone from being customized to someone else’s liking.

[Re-Titled by Moderator]