Twitter, Instagram, and as of recently, TikTok. A couple times here, but I don't know if it really worked out.
People like bonus art! Stuff that makes your comic feel relatable. Memes and stuff! If you have those post them between updates. Also interacting with other comic creators, esp on twitter, participating in art hashtags that apply to you (drawingwhileblack, visiblewomen, etc) get new eyes to your work!