For many erotic scenes you can choose to be the top or bottom, including ones with the bigger hairy guys.
In the beginning of the game Sam is more often the bottom as he is still coming to terms with his attraction to guys. So the other guys take charge more. That shifts as game progresses.
There is no option to add body hair or beard to MC because it would require an extra 1400+ CG renders for each option. But I have gotten that feedback so in the next game I'd give him some light facial hair!
Let me know if you have any other questions!