i dont have it tested yet but maybe cloth can help you there. you prob. need a skelleton to make a basic structure and increase the deforming realism but may work.
since im a complete newcomer to blender (used Cinema4D before) i cant give you any advice or epxerience on that. a “improved” idea i got in this matter is: build the body as a soft-body object and then put the cloth-skin above it. ill test it on a simple mesh and post how it worked out
There’s a better method using the shrinkwrap modifier. There is a muscle rig that uses shrinkwrap as a basis for muscular deformation. I dont have the link to it, just google it.