My DS has a sports scholarship trial on 4th Feb.
If your son is going to be in year 7 then at this age they don't tend to focus on a particular sport but try to make an assessment of all round sports ability. So the tests will be based on 'running, jumping, catching, throwing'. They may also be looking for the ability to listen to and carry out instruction as well as being able to make improvements to technique following advice. The children may be asked to play 'games' in teams to assess the concept of 'sacrificing self for team' i.e. giving up the chance of individual glory to enable the team to win. They might also be watching for reactions to losing.
My advice to my DS has been: listen carefully, try your best, be a team player and a gracious loser.
I can let you know exactly what was involved in my DS's trial after the 4th.
Good luck to your son! Fingers crossed!