All I’m going to say is that I’ve never seen a 40 year old without a significant martial arts base make their mma debut and not get absolutely smashed.
If you don’t have a black belt, wrestled in college, or 10+ kickboxing or boxing fights, the odds are very stacked against you.
I agree with the other guy who said do a bjj tournament and see how you do
Actually I take that back. My cousin who was probably 37 - 40 at the time won his mma debut. This was about 20 years ago and the guy he fought trained in a garage and ended up going like 0 - 7. Similarly aged as well lol