I confirm the point of Narcos Garcia. If you want more control on a new user to create, you can use hooks to create the user then to create a sudoers.d file with the right delegations.
https://live-team.pages.debian.net/live-manual/html/live-manual/customizing-contents.en.html Here an exemple: https://github.com/skhemissa/Rescue-Forensic-Disk/blob/main/build_files/config/hooks/live/0901-create-user.chroot
