If everything works just right, a floc treatment can clear up the pool overnight and an hour of careful vacuuming will remove the settled debris. But it doesn't usually go that way. Floc occasionally doesn't work at all, the water remains cloudy. When it does work, everything settles to the bottom of the pool. To clean it up from there you need to vacuum up everything to waste. Not all pools are able to vacuum to waste. If you can't vacuum to waste, the return flow will disturb the debris on the bottom and prevent you from getting all of it. If you can vacuum to waste, to water level will go down fairly quickly. At some point you will need to refill the pool, and that will disturb the stuff on the bottom and prevent you from getting all of it. The added water will also change your chemical balance, which may require significant adjustment to get back into balance.
Pool First Aid contains enzymes, which you don't need. And a clarifier. There is some chance that a clarifier will help, but more often than not a clarifier will do nothing.
As a general rule, it is a bad idea to add chemicals that you don't really need. The pool will clear up on it's own if you are patient. Anything you add may just as likely cause problems as help.