Its a family plan and they are changing carriers.

There's no reason you should have to change your phone just because you changed carriers, unless its already carrier-locked. I just did this a couple of weeks ago.

If it is, then consider that you're probably going to be stuck in this loop of constantly buying shitty new phones. You should be able to pay it off and get it unlocked, if that's possible. Then look at some MVNOs, they often have much better pricing. Metro PCS, Visible, Mint, etc. There's also some affordable privacy-friendly carriers like JMP.chat, Cape, Phreeli, SimXL, silent.link, etc.

If you just get another carrier-locked device, it's a moot point, so you don't have to worry about it.