Bicycle Mechanics - changing wheels and have a cassette question

I am replacing my wheels and would like to just buy a new cassette and keep current wheels on the sidelines all set up just in case. I currently have a 11-25 and like it but the shop I am getting the wheels from only has 11-28 cassette. Will the bike need to be adjusted for the extra teeth or will everything be fine?

I am replacing my wheels and would like to just buy a new cassette and keep current wheels on the sidelines all set up just in case. I currently have a 11-25 and like it but the shop I am getting the wheels from only has 11-28 cassette. Will the bike need to be adjusted for the extra teeth or will everything be fine?
You have to tune the rear derailleur a bit. Most likely it will work without any adjustment.

It partly depends on how closely (short) you cut the chain. If you cut by the Sram method, ie. big/big + 2 links it won't be long enough for the larger cassette. Test the chain length shifting carefully to the big/big combo (off the bike) to be sure that's no issue.

Then there's a chance that you'll need to fine tune the trim. The cassette to dropout distance varies a tiny bit wheel to wheel and cassette to cassette. Odds are the difference won't be enough to affect the limit settings, but don't be surprised if the barrel adjuster needs to be turned 1/4 turn in either direction.

Lastly it's best if you keep all the chains and cassettes fairly closely matched in wear age. Just like an old chain may skip on a new cassette, a rarely used backup cassette may be too new for a well worn (but OK) chain. When I supported a team eons ago, we made it a point not to have dedicated spare wheels. Instead all the wheels were continuously rotated in and out of service.