Trim the tailpiece to fit.
Bathroom sink tailpiece too long.
I suggest that you do dry run meaning assemble and hand tighten all drain pieces including tail piece first.
If the tailpiece will not line up with the trap move the trap into its original position tighten the collar with the pipe wrench and obtain a flexible tailpiece extension for your drain.
New tailpieces come quite long so they can be trimmed to fit.
If it s too long cut it with a hacksaw.
You doing this for measuring purposes only.
Tail piece should be long enough to be fully inserted into p trap and seal.
There is lots of play so no worries.
If it s too short add a tailpiece extension which is a short length of pvc pipe.
A pipe cutter would be a bit more suitable than a hacksaw but if you only have a hacksaw just clean up well with a file after sawing.
Slide it onto the tailpiece and.