Sunburned plants - what to do

[i luv gardening!]

Hello! We've had some record breaking heat here in SoCal. Super heat like that is uncommon where I am, and it's taken its toll on some of my plants. In particular, boxwood and Peter Pan agapanthus. They're both pretty badly burned. My questions are these . . . can I just shear the agapanthus way back, like almost to the ground? Will it come back in the spring? The leaves are too small and too many to deal with individually. Sort of the same with the boxwood. Can I give it a heavy pruning? I've never done that before. It gets sheared into a small hedge but never pruned. Got any ideas for me? Thanks!