Have, on occasion found them marked with labels like "RADIO" but to be honest.
Find the primary house fuse block, get a test lamp (This is like an ice pick with a light bulb in the translucent plastic handle and a wire with clip) clip the clip on a known ground and go tap tap on each and every fuse in the box (Tap/probe both ends one at a time)
Dark/Dark fuse unkonwn
LIGHT LIGHT fuse goood
LIGHT dark or dark LIGHT, fuse bad.
In the house block, dark dark should not happen (Does happen on the chassis block though).
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times