I would change a few things temporarily.
The new child is trying to learn the football and the social environment at the same time. That is a lot.
Pair them with one friendly teammate in practices, explain any team-specific words before the game starts, and avoid assuming they understand routines everybody else has heard for two years.
I would not redesign training around them or make a big announcement about helping the new player.
Small things normally work better: introduce them properly, give them a familiar partner, and make sure they get early success in the session.
The established players can help too.
At U10, belonging often improves the football quickly because the player becomes more willing to ask questions, call for the ball and make mistakes.
Help them settle first. The team habits will come.
