How close are me and my cousin physically?

My seven-year-old cousin wants to play fight/play wrestle with me. I am going to see him in a couple of weeks, and this is only the second time I have seen him in person his entire life, and not used to being around people his age. Therefore, just not quite sure what to expect. I spoke to him over FaceTime and he was flexing his arms like he was John Cena or something, and his arms looked pretty big and strong, yet his mom says yes a little bit below average seven-year-old.

How effective would his moves, like a chokehold or a tackle be on me? How difficult would it be for me to get out of them? And for him, how effective would my moves be on him? How difficult would they be for him to get out of? Like when he stiffens his arm when we arm wrestle, how difficult would his resistance be? And he applies a strength would it be easy for him to overcome my resistance?

He also wants to have a running race. So again I’m not used to being around people his age, so why should I expect in terms of how fast he runs compared to how fast I run?

I guess what I’m asking is, how close are we in strength and speed? How good of a chance would my cousin have if we both played our best at both of these games? Can you please explain? I’m only used to being around people my age