For pistols,
Properly set, the taper crimp die just removes the bell at the case mouth that the expander die made.
Nothing more.
For revolvers, the taper crimp die is used with smooth sided bullets that don't have a place for a roll crimp to work.
By design, a taper crimp die doesn't make a roll crimp.
And too much taper crimp that applies excessive pressure on the bullet is to be avoided.
It can damage bullets and ruin accuracy and possibly increase cartridge pressures.