It's easy to find stock photos of slim white people doing stereotypical activities -- women laughing alone with salad and that sort of thing. If that isn't what you're looking for, may we suggest some of these sites that break the mould?
Photo by @_willpower_ at Nappy.co
Photo by @eyeforebony at Nappy.co
The site: Nappy.co
What you'll find: "Beautiful, hi-res images of black and brown people. For free."
Permissions: These photos are available under a Creative Commons Zero licence, so no strings attached. Linking back to Nappy and the photographer is recommended, but not required.
Women of Colour in Tech
Photo from #WoCinTech chat.
The site: #WoCinTech chat Flickr photo group
What you'll find: Photos of people at computers -- but all the images feature women and non-binary people of colour. (Many are tech professionals in real life.)
Permissions: Creative Commons Attribution licence. Use these photos however you want, as long as you credit #WoCinTech chat.
Photo by Isaac Brown/Stocky Bodies
The Site: Stocky Bodies
What you'll find: Plus size people doing normal people things, not just sitting on couches looking lazy. Sadly, the images themselves are on the smaller side.
Licence: You're granted permission to use the image without modification, as long as you credit Stocky Bodies.