On Amazon console go to Volumes, Right-click on item attached to your EC2 instance, enter new size (In the example I extended up to 32G):

Extend EC2 ext3

Login into your EC2 instance and write:

lsblk

It will show partitions:

NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
loop0 7:0 0 93.8M 1 loop /snap/core/8935
loop1 7:1 0 18M 1 loop /snap/amazon-ssm-agent/1566
loop2 7:2 0 93.9M 1 loop /snap/core/9066
xvda 202:0 0 32G 0 disk
└─xvda1 202:1 0 8G 0 part /

We see xvda with 32Gb and xvda1 with old size 8Gb, lets extend it.

Run:

sudo growpart /dev/xvda 1
sudo resize2fs /dev/xvda1

Extend EC2 ext3 preview