How is my personal iPhone being "managed" ?!?

My phone has been showing signs of issues or being 'hacked' for a long time now but I don't know how to prevent it from happening again so I've been patient and paying attention to it but it's just becoming too much to handle. The phone is mine through Verizon and I preordered the iPhone 13 Pro Max for myself but it seems to be a 'managed device' which would explain a lot. The list of things that it does or doesn't do is pretty extensive and I think it being managed by someone else is the most important thing to focus on but I don't know who to trust or who to get help from. I can't imagine starting over with a new device and putting three years of the same appleiD into a new one and having it happen again. It has pushed me close to completely breaking mentally and emotionally knowing that everything I do is monitored by someone else and any help is greatly appreciated.