None that I've had either on my iPhone 13 Pro Max or my new iPhone 16e. My iPhone 13 did not have the latest A17 Pro chip and 8GB RAM (same goes for your iPhone 12) so no Apple Intelligence but the 16e does and that works perfectly well too.
Depending on what iOS you are using there will be some changes; Some of the notable additions include the ability to lock and hide apps, new ways to view the schedule in the Calendar app, and extensive personalization options for the home screen and Control Center.