qemu-img can convert many formats.
Here is an example
-f raw = this means the format of the source image (instead of raw it could be vdi, vmdi, qcow2 etc..)
-O vdi = the output format that you are converting to (instead of vdi it could be vmdk or qcow2)
windows2019.img = the source file
windows2019.vdi = the output file (you should give it the extension of the format you converted to
qemu-img convert -f raw -O vdi windows2019.img windows2019.vdi