CapeTweaks is a small mod for vanilla capes. It does not add any new capes.
With CapeTweaks you can smooth their movement, or have them not show up at all! You can also toggle if elytra can have the cape texture. Additionally, you can also hide specific capes, like Minecon capes and migration capes!
CapeTweaks does not add OptiFine capes. For that, see Kappa. CapeTweaks also isn't guaranteed to work with any modded cape.