There are many ways to make a skin. The most common method is via a website editor, as Skeddless, suggested. The method I use is a photo editor/paint tool. I feel I get more control, and customization doing this method. I personally swap between Photoshop, and Paint.net (Just the name, not a link).
There doesn’t seem to be a definite answer I can find to this question,
how and what program is used to make custom Minecraft skins?
https://www.planetminecraft.com/pmcskin3d/
are you able to do this for ps4?
There are many ways to make a skin. The most common method is via a website editor, as Skeddless, suggested. The method I use is a photo editor/paint tool. I feel I get more control, and customization doing this method. I personally swap between Photoshop, and Paint.net (Just the name, not a link).
If you're interested in getting a custom skin made, or simply seeing what you can do using an editor, feel free to check out my thread! It will be updated in the next couple days as well. https://www.minecraftforum.net/forums/mapping-and-modding-java-edition/skins/2864437-professional-custom-skin-making-paid-service