Guys, what kind of program do skins do? (People Playground)

you need to copy textures in the game folders and paste them into some unnecessary one and then change

for this you need to click on the folder with textures and open their image

after that create and better change

in any pixel graphics editor
I use this
https://store.steampowered.com/app/1204050/Pixel_Studio_for_pixel_art