CTRL-right click on the Xref, pick Xref Tools from the pop-up, then pick Xclip. From the side menu you can select Ignore Z (if you don't need to isolate a portion of the Xref in the Z direction), then New Cube, then Polyline, then start running your boundary. Once you've finished that, pick Clip On and only what's inside the boundary you select will be shown.
Highest Regards,
Alan T. Hendry, RA
Intel i7-12700F (2.10 GHz) Desktop, 16GB RAM, 1TB SSD, Win 11 Home 64-bit, DC 23 w/ latest beta
Intel i7-10750H (2.6GHz) Laptop, 16GB RAM, 1.5TB HD, Win 11 Home 64-Bit, w/ DC 22, 23 & latest beta