How to copy root to SSD from SD

Could someone tell me how to copy the root partition on the SD card to the root partition on the SSD drive? I am copying boot and root to ssd to boot KFCE on RPI4 Arm. I get an error as soon as it starts from the /proc directory saying there is no device. I am booting to root to get permissions to copy the partitions…is this the right way to do this? Very new to Manjaro. I have flashed the PI to boot to usb version. Thanks!