Nintendo has official emulators through switch online. They have a limited selection of NES, GBA, GBC, and SNES games available through the standard subscription, and N64 for the more expensive one.

It is technically possible to download ROMs of any game from any consle, and play in superior quality on a PC using an emulator. But my lawyer informs me that some part of that is a violation of copyright laws so you SHOULD NOT do that, despite the ease of obtaining and emulating ROMs of old games.