Most of the brands that approach my fiance expect 5% engagement (likes) and 1% comments for a paid campaign. She has 20k followers and gets 700 or 800 likes on pictures of our dogs, more when she shares a recipe or travel post. Sponsored stuff with a brand tie in is always higher than that.
(Except if we're talking about a pretty girl or something, where the followers are also mild-remote-stalker types).