Looks like you have an outdated iPhone, can’t be update to a higher iOS (iOS 13 and later), no longer meets the requirements for many apps.
The last security updates iOS 12.5.6 -> released August 31, 2022, available for: iPhone 5s, iPhone 6, iPhone 6 Plus.
Check -> iPhone type & iOS version -> Go to Settings -> General -> About.
Then go to Settings -> General -> Software Update -> Download and Install.
Yes, most apps require iOS 13 or later.
Considering a newer type of iPhone?
Read before you buy a newer iPhone:
The All Too Common SAD Reality of Buying a Used iPad/iPhone
The All Too Common SAD Reality of Buying … - Apple Community
Apple Store -> iPhone - Buying iPhone - Apple
Apple Certified Refurbished-> Refurbished iPhone - iPhone 12 Pro - Apple