After a thorough online search for petite leather coats, I've come to conclusion that they are there, but they are not labeled as Petite.
So my advice to you is to look for women's leather coats in general and read the detailed size information.
Usually if the coat is long the seller indicates the length of it. So these coats I found on Amazon actually would fit most Petites. In some cases though you'll need high heel shoes.
As for petite leather jackets, my advice is the same. Look for any women's leather jackets. Depending on your body shape majority of jackets would fit petite women too.
So all depends on your patience to check sizing details. Then take measurements of your body. Revise the style paying attention to its cuff length. Then go for it.