C:\Program Files\qemu>qemu-img resize C:\RaspberryPi\2021-05-07-raspios-buster-armhf-full.img +2G

WARNING: Image format was not specified for 'C:\RaspberryPi\2021-05-07-raspios-buster-armhf-full.img' and probing guessed raw.
         Automatically detecting the format is dangerous for raw images, write operations on block 0 will be restricted.
         Specify the 'raw' format explicitly to remove the restrictions.
Image resized.