Download the ISO at Ubuntu 22.04.3 LTS (Jammy Jellyfish)
Create a new folder for your custom ISO

mkdir ~/customISO

Mount the CD to /mnt

mount -o loop /path/to/ubuntu.iso /mnt

Copy the CD to your custom ISO folder

cp -r /mnt/* ~/customISO/.

Create an autoinstall folder

mkdir ~/customISO/autoinstall

Create your user-data file

vi ~/customISO/autoinstall/

You can either create a fresh file (see Automated Server installer config file reference for help) or if you already installed a system manually, you can use the same config and modify it. Its located at “/var/log/installer/autoinstall-user-data”
The meta-data doesnt need any content, just create it

touch ~/customISO/autoinstall/meta-data

Automated Server installer config file reference Automated Server installation - Introduction Automated Server install quickstart Ubuntu 22.04 Server Autoinstall ISO