Xentuner
This plugin is for MuseScore 4 and is intended to allow microtonal/xenharmonic composition with all the accidentals MuseScore supports. Since there is already good support for the graphical accidentals, this plugin only affects playback. The way it works is you create a file representing how you want the naturals (notes A-G) to be tuned, and by what amount each accidental should modify a pitch. Then just run the plugin and a tuning adjustment will be added to each note so it actually sounds in your tuning. See the example files to understand the format and what is possible.
Note that for MuseScore 4.2+, certain of the accidentals already have built-in pitch modifications, so the extra modifications added by XenTuner are only the delta between those and the default pitch modifications. For example, a quarter-tone sharp symbol has a default pitch modification of +50 cents. In 31edo, it should instead be 38.7 cents, so XenTuner will assign a "tuning" value of -11.3 cents on top of the built-in +50 cent modification.
In MuseScore < 4.2 there are no built-in pitch modifications for any microtonal accidentals so the "tuning" value is the difference from 12edo.