"Yes. The Lee 4 die set comes with the Lee Factory Crimp die, which does a taper crimp."
Yes, BUT, to get a little more specific, in auto pistol rounds the FCD is a taper crimp. In revolver rounds, it's a roll crimp. In rifle,(bottleneck cases), it's a collet crimper that forces the extreme end of the neck sideways into a crimp grove, or will crimp into a plain bullet as well.
Basically the 3 and 4 die sets are the same up to the FCD,(final crimp die). the 3 die set has as it's 3rd die a seater with a crimper built in. You CAN seat AND crimp in one pull of the handle. Most people do NOT do it that way. It's tuff to get the timing down just right, and the case length is critical. Most seat first, then, in a seperate operation, set the die deeper to crimp,(the seating stem is backed out to do this).
With the four die set, you simply seat with the third die and crimp with the FCD. The FCD also has a carbide ring in it's base that irons out any lumps or bulges that may have been caused by seating the bullet.
Rifle die sets from Lee are available as deluxe sets, which includes their FCD for that caliber rifle. They are NOT available in all calibers though. Lee WILL make a special die for you in a caliber that they don't offer on a regular basis. You have to send them a sized case of correct overall length so they can get the length right. IIRC it's a $50.00 deal, but worth it IMHO.