The best time to handle crabgrass is in early spring with a preemergent. Look for something that says crabgrass control. If you want to do an early fertilizer application, they make products that come in tandem like this. This far into the season, the best way to handle crabgrass is by spraying. If you have a lot of it, a tank sprayer and concentrate is the easiest and by far, cheapest. Otherwise just a premixed container.
The ones I linked are just examples. You may want to read the reviews to see which brands get the best results on crabgrass.
Edit to add that like I said, crabgrass is easy to control in early spring, and after re-reading your post, it sounds like you’ve got a lot of it now so you may want to go with something like this for the rest of this season. Especially if you don’t already have a tank sprayer.