I have planted perennials I never had before. I don't know if I should cut them back in the fall like we do for hostas and others. They are: Jupiter's Beard, Gaura lindheimeri, Golden Groundsel (rudbekia), bugleweed, aster, serbian bell flower, wormwood-Powis Castle, Chrysanthemum.
Cutting Back Perennials in the Fall
Certified GKH Gardening Expert
I'm listing links for the plants you mention.
You generally can leave most perennials to die off themselves. I choose to leave some for winter interest, Black Eyed Susan is quite lovely in the winter.
Cutting the plants back to about 4 to 6 inches in height at the end of the season can help neaten up the garden and make spring clean up easier.
This will help with pruning and winter care.