Here are a build for John's body.
It just makes John's forearms bigger.

To install, just put the "player_three.ymt" on your stream folder.
If you don't have a stream folder, put the stream folder in your lml folder.
If you don't have a lml folder, huh... What are you doing here ?

If you don't like this build, it's quite simple : Install ExpressionEditor and ExpressionEditorUnlocker from SgtJoe
https://www.nexusmods.com/reddeadredemption2/mods/1144 / https://www.nexusmods.com/reddeadredemption2/mods/1727
And follow the instructions.
Congratulations ! You'll be able to modify yourself the body of John.