For one thing, I’d go used, lots of good condition 26er tyres out there now with people upgrading changing wheelsize.
Hard to say what you need though, if they’re OE spec mountain kings there’s a fair chance they’re absolutely terrible… So you could get a massive upgrade easily. But if they’re quality mountain kings, they’re actually alright.
You’ll never go too far wrong with a pair of highroller 2.35s tbh. Supertacky or 3C on the front, 60a (maxxpro) on the back. Never the best, never the worst, just sensible allrounders that’ll do a bit of anything.