Login to the EC2 Console.
Go down to Elastic Block Store.
Select Volumes.
Select the volume
Click Actions and then Modify Volume.
Enter the new size and click Modify.

At this point, you will need to extend your volumes and partitions.

In this case, I was not using LVM, so it was a pretty simple process.

Check to see which partition you want to extend:

$ df -hT
/dev/xvda1 xfs 8G 8.7G 8G 97% /

Determine the block device and the partition number:

$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 8G 0 disk
└─xvda1 202:1 0 8G 0 part /

Expand to partition to all the available unallocated storage on the disk:

$ sudo growpart /dev/xvda 1

Verify to see if the partition has been extended.

$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 30G 0 disk
└─xvda1 202:1 0 30G 0 part /

Extend the filesystem on the partition:

$ sudo xfs_growfs -d /

Verify:

$ df -h
Filesystem Type Size Used Avail Use% Mounted on
/dev/xvda1 xfs 30G 9.1G 21G 31% /