Create a bootable USB using the dd command.
The dd command below will copy content of the ISO file ubuntu-24.04-desktop-amd64.iso to device /dev/sdd, which in our case is a plugged in USB drive.
$ sudo dd if=kubuntu-24.04-desktop-amd64.iso of=/dev/sdd bs=1M status=progress && sudo sync
Depending on the size of the ISO file and the speed of the USB drive, it may take several minutes to complete.