Can't transfer data through iCloud, manually, or phone to my new iPhone 16 Pro Max

I am on my second 16 Pro Max. Can not transfer through iCloud, manually, phone to phone. Only transfers some contacts. It’s supposed to mirror my phone. It looks like it just came out of the box each time I paired them. Finally gave up after taking the day off of work and being on customer care and apple support for 5 hours today. I even screen shared with Apple support who was truly trying everything and was so helpful, and her conclusion was she tried absolutely everything and it’s the phone. This is my second phone. Bought one in store last week and had almost same experience, but worse because T mobile associates were rude and acted like they were mad I was making them work instead of playing on their phone or taking their breaks. There is a definite issue with this version. I am so disappointed. I am back on my 12 PMx and I still had to troubleshoot on my own to get it fully back to working the way it was. Is this an issue all over? Because from what I am reading it seems like it isn’t just me

[Re-Titled by Moderator]