If I have groups of 2 players but want to create a random matching of 6, what should I do? Because I would like that yes, these 6 play each other every round randomly but in pairs of two so that I keep the ID of player 1 and player 2.

Hi,

I am sorry, I don't quite understand how exactly you would like to match players. Anyway, I hope these pages can give you some ideas:
https://otreecb.netlify.app/rolesandmatching/matching.html
https://groups.google.com/g/otree/c/atR08tLhw28

Regards,
Valery