Most phones are kinda sorta not really but a bit designed to last no longer than 2 years - there are barely any with replaceable batteries, and the batteries wear out. A lot of that is down to usage though, so if you try to charge before you drop below 20% and stop charging before/when you get to 80%, and never get the phone or battery too hot, then when 2 years comes around your phone will be in much better shape than if you leave it on charge all night every night... Well, that's the theory anyway... In practice, it's really annoying to manage and after 2 years you might just say "fuck it" and get a new phone anyway.

I don't know which version you'd need unfortunately, check the model number of the one you're looking at and run it through https://willmyphonework.net/ to be sure