oooh I've already thought about this quite a bit! my sonas are pretty much all part of my headworlds so I've thought about where they'd live. I have quite a few so I'll just include my mains and some secondary sonas.

Clover (main sona) - one-story townhouse in desert suburbia, sliding glass door to a grassy fenced-in backyard with a little garden, marble-top bar separating the kitchen and living room has quite a few potted succulents in colorful pots. Lots of fun little pops of retro and rainbow colors. They'd have shelves full of their Pokemon collection and consoles to play games. Yoga mat + weights for working out too. and their bedroom is dim and cozy with a big quilted loft bed and a big desk for work/gaming/streaming. and their comfort stuffed animals, fairy lights, etc

Raven (halloween sona / glitched clone of Clover) - apartment in autumn town, Halloween meets gamer decor. Blacks and dark greys, hanging Halloween decorations, lots of posters of alt & rock bands, cryptozoology and UFO stuff. their ADHD and sensory issues get the best of them so it's dim-lit and messy, they're also the type for beanbags and have a big flatscreen for gaming

Maximilian (alt main sona) - old-timey but nice apartment in a cozy town! lots of browns and sepia tones, probably have a nice fabric armchair and lots of books. big windows with thick draping curtains, vintage decor, a writing nook with a typewriter

Coffee - a small hut on a tall rock spire over the ocean, connected to the mainland by a wooden bridge. they spend most of their time away from home so it's mostly a storage for their art supplies, canvases, trinkets etc. probably have some cute flags, garlands and windchimes hanging outside

Rainbow - lighthouse cabin with pre-modern retro feel. lots of open space, tables for mail and stationary, lots of natural light, couch, rainbows painted on the walls, vivid circle rugs. their kitchen cabinets are definitely painted in colorblocks, maybe some kitschy stuff in there