Same. My Galaxy S10+ is paid off, and according to Verizon yesterday, they’d give my $650 credit to trade it in for an S21 Ultra. I left it sitting in the cart all day while I pondered, then when I decided to pull the trigger, I saw something on the website about $800 trade-in. Like you, I’m thinking that would be to add another line of service. I was literally just getting online to do more research.
I’ve just been on the fence about whether it’s worth the upgrade to ‘5G’, since true 5G is only available in small pockets of large metropolitan areas; everywhere else, I get the impression it’s essentially souped up 4G. Both my kids have 5G phones and say the difference is noticeable, but actually connecting to ‘5G Nationwide’ is a crap shoot; my son gets it in front of his apartment building and in the underground garage, but not in his apartment proper.
Edit - Yep, $1000 credit toward the phone with a new line, and the $650 offer expired yesterday. Now it’s $440.
2nd edit - I got the $650 deal after all. New phone ordered.