Leo would be down for basically anything. TBNL and maybe Sofia would step on someone if they asked but probably make fun of them in the process. Caspar would probably kiss someone's feet if they asked and he really liked them, but wouldn't have active interest in it himself compared to just making his partner happy. Wes, Ruby, and Emerald would not want to participate in that fetish (and Ruby would probably be disgusted).

The only character who's actively had a foot fetish in the Leo comics is Inalao, but he's not a part of the main cast.