I have a couple of .mxt files i have used in ArcGIS desktop (10.4) that are architectural/engineering style borders for our various size plots, Arch D, Arch E, etc, that include company logos, project id boxes etc. Can i bring these existing .mxt files into ArcGIS Pro to add to my layouts there?
I believe that form ArcGIS Desktop 10.0 on wards mxt's are saved as mxd's for print templates. I mean even the system print templates available in C:\Program Files (x86)\ArcGIS\Desktop10.5\Templates\ExportWebMapTemplates are also mxd's.
So if you have the mxd's with you, you can simply Import an ArcMap document—ArcGIS Pro | ArcGIS Desktop
I hope this helps!