Pre-exhaustion is a popular method many bodybuilders employ. It involves performing an isolation movement before a compound movement to fatigue the muscle before the heavy lift. The idea is that it might increase muscle activation in the compound lift since you have to recruit more muscle fibers to produce the same force, but studies show that’s not the case. Perform compound movements first in your workout, then finish with isolation exercises. If your goal is to fully fatigue the muscle, immediately perform an isolation movement following a compound movement to fatigue a target muscle. This method is safer and allows the same benefit.
Reference: Augustsson, J., Thomee, R., Hornstedt, P., Lindblom, J., Karlsson, J., & Grimby, G. (2003). Effect of pre-exhaustion exercise on lower-extremity muscle activation during a leg press exercise. The Journal of Strength & Conditioning Research, 17(2), 411-416.