Best relevant example would be gorilla tactics Galarian Darmanitan equipped with a choice band. Another includes a burned Jolteon with quick feet holding a choice scarf. Or even a burned conkeldurr with guts holding a choice band.
Normally factors are multiplicative in Pokemon games, so you can naturally assume they are, but in the case of adaptability, it's additive. Stab is 2x, which is an additive 0.5 multiplier to the existing 1.5x stab.
Following adaptability as an example you might think that sniper would also be additive. Which would make crits 2x damage, but it's multiplicative like most other things, making it 2.25x effective in the event of a crit.
I would like to think adaptability as special, and all other values in Pokemon are simply multiplicative, but it would be nice if someone could confirm this for me.