Depending on where it is, if the old capacitor has dried out and not up to value, replacing it will restore the punch to the power supply by returning the "tank" that holds the energy back to the correct value.
If the amp has no conditions of degraded capacitors, it’s hard to say for sure if replacement will give you any benefit. Different brand capacitors will give different results. I use F&T capacitors for most of my amps. I use Sprague Atom for Fender usually and Trainwreck stuff exclusively. Nichicon also makes good capacitors.
If they are failing yes you might get an improvement but if they test up to spec and are not humming etc probably not.
Generally you find that new high quality output tubes correctly biased are a more likely method of restoring punch.