Is it this or one of the shrubs rebecca?
Those seed heads look splendid in winter with a frost on them but they can be cut back
You can cut it back but also I'd dig it up in autumn, split it up and replant a few of the best bits. This is a big plant in a few years, not tall but spreading
My is having a very good year. I think it's doubled in size
If it is the herbaceous perennial type that dies down in winter, it is easily split in spring. It will have big seeds that grow easily as well.
is it the perennial type , like the one nutcutlet sent the link to or the shrubby phlomis fruticosa?( I don't know how to post links, sorry, but you could google it) The shrub form can be cut back, but wear a nose mask as it's covered in tiny hairs which get down your throat and cause days of trouble. I speak from bitter experience.