What to do with an ugly light switch under a beautiful family picture?

what about covering the plate in fabric?

https://tidymom.net/2010/fabric-covered-switch-plate-tutorial/

Can use wallpaper or peel and stick, paint or buy a new one that looks good with the pic.

put In a new light switch. They are super cheap.

Odd one here . . . I would display the family picture elsewhere. And yes, still upgrade the switch plate.

Purchse a decorative switch plate

I agree. purchase a decorative switch plate that closely matches the picture frame.

Paint the switch plate to match the frame, or to blend into the wall color.

I have been going crazy painting all of my switch plates with rustoleum hammered spray paint to match my walls. I have used the brown and it is beautiful, doesn't look like a dark color just a glossy high end look.

You could always decoupage something on it. I have done napkins and pictures that I printed on thin scrapbook paper. Just make sure to do about 4 or 5 coats and they hold up really well. I would wipe mine down often. You could also use contact paper.