The following commands will extend Linux Boot drive without a reboot.

List block devices. Check disk sizes.

lsblk
df -h

Determine file system type: xfs, ext2, ext3 or ext4.

file -s /dev/xvda1
# or
df -Th

Extend volume from the console or command line.

aws ec2 modify-volume --region us-east-1 \
--volume-id vol-xxxxxxxxxxxx --size 10 \
--volume-type gp2

Resize Linux partition.

# for /dev/xvda1
growpart /dev/xvda 1
# for /dev/xvda2
growpart /dev/xvda 2
# for ext2, ext3, ext4
resize2fs /dev/xvda1
# for xfs 
xfs_growfs /dev/mapper/root
xfs_growfs /dev/xvda1

Check if new file size is being displayed.

lsblk
df -Th