Sparring Question

Hey, I'm 15 years old and started kickboxing around a month ago, I've boxed since around December of last year so I'm still extremely new but I'm pretty experienced with sparring. Whenever I picked up kickboxing I decided to move to a gym that specialized in kickboxing/bjj, my experience has been great so far, but last practice some new guy came in that had left for a fight, and whenever we got to sparring it seemed like he wanted to showboat how good he was because he was fighting at full force. Now I'm not huge but I'm definitely not small, I'm 5'11 and 195 pounds, and this guy is around 22 and in the 135 area. I've already told him to lighten up a little but he said alright and then did nothing about it. I'm not quite sure what to do, I don't want to try to intentionally mess him up because I'm 50~ pounds more than him, but I'm also not gonna deal with this shit everytime I have to spar with him, could someone experienced with this give me some advice? Please, and thank you

Also forgot to mention before, but my old boxing gym primarily had people that had been boxing for 10+ years so I'd never run into this issue before, seeing they were extremely nice to me.