Club championship is flighted, but not by age. Single figure’s to enter, It’s a 36H qualifier and then knockout match play for top 16. For 10 cap and above there is a Mid Cap (18 H qualifier, then knock out). Seniors is 55 and over.
On the point of kids playing, my old club championship was frequently won by juniors, and juniors frequently made up up large parts of the men’s teams. Golf (competitive) is by and large a meritocracy in Scotland.