Acrylic paints for fabric give the best results. In my opinion of all the acrylic paints that I've tried, Artistro is the best: https://artistro.com/ Their acrylic markers are great too. I've used them not only on leather, but on glassware and on wood as well
To finish leather, it’s better to use a specialized elastic fixative. But good acrylic paint is durable enough. So, you can decide by yourself whether to use it or not. In any case, the paint will wear off over time. The main thing is to wear and clean leather carefully.