iPhone 12 marked Lost, unable to open due to deceased owner's Face ID

My husband, I have a family plan that included our next-door neighbor who passed away last July, and when I was experiencing issues with my phone a couple days ago, he gave me the deceased neighbors iPhone 12 to be able to get online and figure out how to fix my phone. Somehow in all that I managed to mess everything up because I must have some more of the settings indicated that the phone was lost. I’m not an idiot And I understand how that might be hard to believe for the fact that I’m on here, asking for help by because I accidentally marked a phone as being lost. So I do not know and I have already spoken with support at length and short of going into the AT&T store where the phone was purchased because it is in my husband and he did purchase the phone. I don’t know the his Apple account address The only thing I do know is the pin code to open the phone where I run into a problem is where because it’s marked boss. It’s completely locked down. Other than to make an emergency call or they’re called to call a designated number, which it happens to be my own phone number. He had me as the person to call if the phone was lost and where I run into the big problem or the the only problem is that once I put in the code to open the phone even though it’s marked, lost it then asks for Face ID. Clearly, he is deceased. He passed away last July. it’s how do I bypasses. Can I just anyone out there know anything of how to fix this without having to go through the hassle of tracking down and proof of purchase of the phone and all that I mean I will if I have to. But if I can get any help from anyone out there, I’d appreciate it.

[Re-Titled by Moderator]

Original Title: iPhone 12 accidentally marked Lost, unable to open due to the fact that it requires Face ID and the person who had been using the phone has since passed away