Unfortunately, for Minecraft Java Edition, there are no skins that will automatically incorporate a cape. However, in Bedrock Edition, there are some skin packs that come with capes included.

Skins and capes are pretty common in Minecraft. Most gamers don't use the standard Alex or Steve skin that the game provides.

How to Equip your Cape? Java Edition Open Minecraft Launcher and go to the Skins tab. Select the Skin and click on the option Edit to choose the Cape. Save the made changes and then launch the game.

The new "Minecraft" snapshot 21w03a includes some pretty awesome additions like the Glow Lichen, the Glow Squids, and even allowing players to make neon signs!