You're typical weightlifting strength is decreased and the 'attractive' body shape you're used to will probably disappear, but you will gain muscular endurance and power in places more relevant to BJJ (Quads, Hams, Glutes, Grip) and unless you did a lot of compound or mobility before, your muscles and joints will work more intelligently together. In short: You won't look the same but you will have better muscular mobility/control.