Do you ever trim Autumn ferns when they get too tall?

Question

They are planted in front of boxwood shrubs and they completely hide the boxwoods.

Answer 1

You can cut back old fronds after new growth begins in spring, but I would not "shorten" fronds. That would not look good. Better to move it to a place where it can shine in all its glory.

https://www.gardeningknowhow.com/ornamental/foliage/autumn-ferns/autumn-ferns-in-gardens.htm