Turn the retreat rule into a habit rather than a gift that gets wasted. Spread out while the space exists, play out along the ground, get the ball to a player who can face forward, and get it past the line before the press arrives.
Play 4v4 plus keepers on a 40x30m pitch with a goal at each end. Mark a retreat line across the middle. Whenever a keeper takes possession, whether from a goal kick or in open play, the whole opposition must drop behind that line. They may press again as soon as the ball is in play, which means once a second team-mate touches it or it crosses the line. Keepers roll, throw or pass along the ground and never punt. Count a goal double if the team built the ball out through the line rather than kicking it long. Play short games of five or six minutes and rotate the keeper.
Very few rules in youth football exist to teach something rather than to regulate it. The retreat line does. When a keeper gets the ball the opposition has to drop away, which manufactures a pocket of calm that would never happen naturally, purely so that young teams can learn to start an attack properly without being punished for trying.
Most teams then throw it away. The keeper kicks it long, the ball lands in a crowd, and the few seconds the rule handed over are spent doing the exact thing the rule was written to discourage.
Rehearsing the pattern once in a static practice is not enough, because in a match the rule fires again and again, at every goal kick and every save, and each time the picture is slightly different. That is the argument for training it as a game rather than a drill: the decision has to repeat.
The first job is spreading out, and it has to be immediate. The space only exists while the opposition is walking backwards. Two defenders standing near their own posts have converted a numerical advantage into a straight ball down the middle.
The second job is a third option. A keeper with two choices is a problem a pressing team can solve. A keeper with three, one of them a midfielder dropping in, is arithmetic they cannot cover as they arrive.
The third job is knowing what happens when the press does arrive, because it always does. Whoever receives should already know whether they are carrying or passing, since working it out afterwards means working it out with somebody running at them.
Scoring the game double for a goal that was built out rather than booted out is worth doing. Young players follow the scoreboard far more reliably than they follow instructions.
Save it to your private drills, then change the animation, adjust positions, swap equipment, or drop it into a session block. Or start from a blank pitch and build your own.