There are a few options in Bedrock edition: you can import a .png file just like in Java edition (but only on PC), heavily customize individual parts of your skin using the Dressing Room ...

Minecraft Java Edition has some of gaming history's most ... which contains a long list of png files for each and every block. Simply open one and edit the texture however you want.

If you've ever played Minecraft Java Edition, you probably recognise ... This image, called pack.png in the game files, is seen in two places in Minecraft: in the resource pack selection screen ...