Make boot SD image

# clone SD image
sudo fdisk -l
sudo umount /dev/sdb1 /dev/sdb2
sudo umount /dev/sdb
sudo dd if=/dev/sdb of=~/RPi.img bs=8M status=progress conv=fsync

# restore to any larger card:
sudo dd if=RPi.img of=/dev/sdb bs=8M status=progress conv=fsync

Using PiShrink

sudo apt-get update
sudo apt-get install wget parted gzip pigz xz-utils udev e2fsprogs
wget https://raw.githubusercontent.com/Drewsif/PiShrink/master/pishrink.sh
chmod +x pishrink.sh
sudo mv pishrink.sh /usr/local/bin

sudo pishrink.sh RPi.img RPi_shrunk.img

# restore to any larger card:
sudo dd if=RPi_shrunk.img of=/dev/sdb bs=8M status=progress conv=fsync

Usage: pishrink.sh [-adhnrsvzZ] imagefile.img [newimagefile.img]

-s Don't expand filesystem when image is booted the first time -v Be verbose -n Disable automatic update checking -r Use advanced filesystem repair option if the normal one fails -z Compress image after shrinking with gzip -Z Compress image after shrinking with xz -a Compress image in parallel using multiple cores -d Write debug messages in a debug log file