Is it correct to write
The Hampshire EJCOA Championships Qualifier is for all chess players who are aged 21 years or less as at August 31st 2023.
or
The Hampshire EJCOA Championships Qualifier is for all chess players who are aged 21 years or fewer as at August 31st 2023.
or
The Hampshire EJCOA Championships Qualifier is for all chess players who are aged 21 years or under as at August 31st 2023.
or
This is utter bo**ocks and John should go back to the drawing board
Your opinions, as always, will be most appreciated.
(My preference is for fewer rather than less)