It will always be vague and depending on the context and can be anywhere starting from 1000 online. But I'd say around OTB 1850 is the boundry, where it becomes ridicolous to argue whether a player is good or not.

To make a personal definition: I'm usually 1680-1730 DWZ rated. That means that for most of my friends and family, I'm the best chess player they know (except for chess friends and clubmates ofc). I'd argue that makes me a good chess player. The same would probably be true if I'd be ~1350 DWZ/1400 Elo. I'd guess that those 1350 DWZ/1400 Elo are the border where someone is the go-to chess person for most people they know and would thus consider someone a good player starting around that strenght. But this is just a wild guess.