Unless you will be using only pretty thin leather, you will have to get a purpose built sewing machine.

I am not an expert on sewing machines, but have made a number of things out of heavy canvas. When I started doing that, my mom got a me a used Singer. She made a point of an older one because they had steel gears, not nylon, like all the newer ones (except industrial ones). I have used that thing on a lot of very heavy fabric for 15 years, and it is still kicking.

jim