The bridge to the Run/Pass game is called a Play-Action Pass
It’s a concept where the offense attempts to sell the run, and then the QB hits an open receiver. Simple concept, but it has to be worked on over and over to make it convincing. Just as WRs try to make as many of their routes look the same. The RB wants his real running plays to look as much like as his fake/PAP running plays so that the LBs and defense think he still has the ball and commit to stopping him. The QB is the same way on making handoffs and fake handoffs look identical If someone bites on the fake, then the QB can usually capitalize on their mistake.
Below is a redzone play-action pass (PAP) where the running back runs a 25 off tackle play and then turns it into a flat route. The X runs a comeback. The TE runs a drag, the Y runs a 12-15 Hook/Curl. The FB in this case is initially responsible for chipping/blocking the ROLB, and then he releases into a Settle route near the goal line.
If you notice the red arc that is shown, it is the pocket that the OL form. The purple lines are for the guards to flow out to the edge if their ILB’s drop to a zone or cover a receiver on a route.
The better offenses have multiple play-action passes off of each run. They make an offense more dynamic and harder to defend. This was just one example of many.