This is a long series of notes from early 2024 forward, and they can help you understand how to work with color palettes in a SNES rom. Everything here is based on the Final Fantasy V rom, which you can find at archive.org if you search for SNES roms. The tool used to edit the bytecode is Mesen, which you can find here.
1st Palette - for the heroes and many NPCs ($1FFC00)
08 25 A5 14 3F 53 9F 3E FF 7F FF 03 38 02 74 01 FF 7D DF 3C 5F 01 E3 6C D9 7C CE 7D 11 1F 80 02

2nd Palette - for NPCs, Syldra, & some monsters ($1FFC20)
CE 39 A5 14 3F 53 9F 3E FF 7F FF 03 96 2E CE 7D 1B 00 1B 19 6E 1D 94 52 40 53 20 3E 13 7D 10 70

The first 6 appear identical (the clear color doesn’t show).
After some chats with Zozma and seeing how he radically modified the map palettes in his FFIV romhack, I’m considering adjusting these palettes to make them less bright. If the colors are amended slightly they may open up new options for recoloring the NPCs, too.
This is Galuf’s unused Mime (aka Mimic) Job palette. I used Mesen to find this data, from debugging a running smc file.
19 21 84 10 FF 7F 88 0C 3F 43 38 02 20 7E E0 7C
F8 31 74 01 9A 02 FB 14 11 00 BF 3F A4 0A 53 01
I used three different Mesen Debug apps to find these bytes: the Tile Viewer, Palette Viewer, and Memory Viewer.
Then Right Click anywhere in that palette and choose View in Memory Viewer.

Mesen will open the 3rd app and show you the bytes behind the colors.