Assuming that the obvious as stated by Keyzer is in place, then I'd go for the following:

Create an identity and a way of playing that happens across all the age ranges and the first team, so each side play the same sort of football. This would be done with the DoF and they would oversee the implementation of this. That way, players making the move from one age range to another, particularly from the under 23s to the first team, can slot in far more easily as the type of football would be virtually the same. Same formations and style of play, with allowances for changing things if needed depending on the opposition, but there would be a general similarity.

If the club is to progress up the table and to the Premier League, having players who are comfortable on the ball and can pass accurately is a must. The idea is that a side would be created that could adapt to the Premier League. Swansea, Brighton and Brentford are all sides that, to me at least, have had promoted sides that didn't look out of place in the top division. Players who aren't comfortable on the ball are sold/released. Data experts at the club target players who fit relevant criteria. Young players are given decent opportunities and I'd have some stability in the starting line-up, not chopping and changing 3-4 players every game. Players need to learn each others' games.

I'd expect the first season to be a struggle. Some fans would be impatient with a different style of football, which I would base on keeping possession but being quick and direct in the final third. If we have the ball, the other team can't score. Players would need to get forward, crosses and cut backs put into dangerous areas where I'd expect players to be. Having spells of possession can act as a breather as there would be a big onus on midfielders to get into the box to support strikers. In training we'd have a rule of if we lose possession, 5 seconds to get it back.

We might not be near promotion after 2 seasons but we'd have a blueprint for good, attacking football and battling to win back the ball, not sitting deep and inviting pressure. That blueprint, with those Keyzer has suggested, should set the club up for an eventual promotion where we look ok and survive in the PL, but we still keep the plan.