If you’re considering running a closer ratio cassette, I’ll be the first to suggest dropping from 3 rings to 2 (or even 1) up front instead.
You’ll find some people love closer ratio cassettes, but I like most others I’ve spoken to that have tried them find that you’re forever changing gear, and often 2 at a time, and you change rings up front more often as a result too. All a PITA on a mountain bike.
For this reason, maintaining a wide(r) range cassette, and dropping to just 2 rings (or even 1) up front makes more sense…