I will seal the endgrain of legs with an epoxy if I expect them to be used in damp areas, or outdoors.
Otherwise, any paint or varnish finish you put on the bottom of a leg will eventually wear off, and usually leave behind ugly streaks on a nicely finished floor.
A replaceable hard felt pad is the preferred end for a table leg on a carpeted or finished wood floor. Go for the ones that are self adhesive, rather than held on with a tack or screw. Those with metal fasteners will scratch as the pad wears down.
I you want to use leather, check with Landwerlen Leather in downtown Indianapolis. On Illinois St, across the street from the bus and train station. He has better prices than Tandy on the west side.
If you don’t want to cut up belt blanks, Landwerlen also sells replacement shoe soles. The leather on these is a little thicker and tougher than the belt blanks. Barge leather cement can be used as a very strong contact cement for attaching leather to the bottoms of chair snd table legs. Apply a small amount to both the leg bottom and your leather piece. Let them dry to a tacky stage ( about 5 -10 minutes) and press together. You can use a hammer to improve adhesion.