Some players will be forced to retire due to injury, so I'm not sure of the actual statistics, but it's not abnormal to find players well into their 30s.

If it helps, here's the current squads for a few of the northern hemisphere teams with their ages listed. Lots in their 20s but a few current players have passed 30.

https://en.wikipedia.org/wiki/Wales_national_rugby_union_tea...

https://en.wikipedia.org/wiki/Scotland_national_rugby_union_...

https://en.wikipedia.org/wiki/Ireland_national_rugby_union_t...

https://en.wikipedia.org/wiki/England_national_rugby_union_t...

https://en.wikipedia.org/wiki/France_national_rugby_union_te...

https://en.wikipedia.org/wiki/Italy_national_rugby_union_tea...