Using duplicate exactly for external drives

I need to copy or duplicate about 4TB of photos from one external drive to another external drive (the original one is getting old and is too small). Im thinking the duplicate exactly might be the best way but am not sure. I use them with Lightroom Classic. My first external drive does not have enough space to duplicate on that drive. Is there a way to use the duplicate exactly to put it on a new external drive. I want to keep a copy on the original external drive.