Play a real game in miniature. Keep the ball to move the opponent, support the player on it with width and depth, combine to create the chance, and defend together the moment you lose it.
Mark a 30x20 yard pitch with a goal and keeper at each end, 3v3. Play a normal game: score in the opponent's goal, defend your own. Keep the games short, three to four minutes, and rotate teams. Coach the basics of support and shape, always an angle for the ball, defend as a unit, and quick decisions the moment possession changes.
Below three players a side, the game stops containing football. A 1v1 is a duel and a 2v2 is a partnership, but neither has a triangle in it, and the triangle is where support with width and depth becomes possible rather than theoretical. Three against three is the smallest format in which every element of the full game is present: keeping the ball, moving an opponent, combining to break a line, defending as a group, and a goal to attack and one to protect.
That is why it is worth more than its size suggests with young players. Everything you would coach in an eleven-a-side match exists here, at a scale an eight-year-old can actually perceive, and with roughly ten times the involvements per player.
The support angles are the thing to coach, because they are what the third player makes possible. One teammate offering width and another offering depth gives the ball carrier two genuinely different options, and young players default to giving him two versions of the same one by standing at similar angles.
Drawing the press and playing into the space it leaves is the next layer, and at eight it is a big ask. Expect it occasionally rather than reliably, and name it loudly when it happens.
Defending together is half the format and gets a fraction of the attention. The moment the ball is lost all three players have a job, and the common picture is one child chasing while the other two watch him do it.
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.