He was not the Commander in Chief who oversaw the implementation of the Doha Accords. Nor was he the Commander in Chief during the accelerated withdrawal from the 8,600 troops to the bare minimum needed to support the Afghan Army in the field, 2,500. With Trump as CiC the so called Conditional Withdrawal's was not based on the Taliban achieving the conditions of the agreement, is was more like "We're gonna Skedaddle as long as you don't shoot at us" Accord.
Biden didn't change that either. But he started with the 2,500.