Export an instrument part in a new key

I have a trumpet duet created in Dorico. I would like to print out the first trumpet part but in a different key. is there an easy way to do that?

Yes, there is!

Layouts can have the same player but a different transposition: Help page on Transposition Overrides

You can easily use this if you want the same part for Horns in F and Eb, or for Baritone in bass clef and treble clef.

Thank you. I will check this out