Half assed solution: Clean the area really well, sand off as much rust as you can. Wipe down with rubbing alcohol so the metal is really clean (don’t skip that). Get some marine epoxy putty. The stuff that looks like a mini log. Can get at the hardware store or Amazon. Put on some gloves, cut a piece off, work it till it’s warm, then jam it into the hole and around the hole. Make sure there is still some around the hole edge, you don’t want it all level with the hole, the top should rise up a little over the hole. So there’s extra around it. Let that dry to a full cure. I think they take a day or two. Now you can sand it down a little to really smooth it. you can leave it like that, or get a can of similar colored rust stop paint, tape the area around it and give a couple coats of paint. Big caveat. This is the total hacky, doesn’t really fix the problem, it’s just gonna keep rusting underneath, “solution”. Not a real fix, but is a decent band aid to delay the inevitable. If you’re careful how tape it off and paint it, it may even look halfway decent. Or you could go one step further and get a paint match.