I may need more coffee (and I do), but I see a simpler solution, if the OP has not already performed the above.
And welcome to linux.org @Nourr
Yes, if you have your installation stick, or a GParted Live stick.
If installation, boot from it, and choose Try Ubuntu before installing. I would switch off power saving features so the process is not interrupted.
Go to your applications launcher, search for and open GParted.
Check for available unallocated space immediately following or preceding your root partition. If your root partition has an icon of a padlock or key or similar beside it to say it is mounted, unmount it.
Use GParted to adjust the size of the root partition to expand to incorporate the additional space you require, and OK that.
If the preview appears to be satisfactory, click the check mark at top whose quick tip shows something like apply changes and the operation will proceed.
Once completed, leave a few seconds and then close out of GParted, power down your system and remove the stick.
Reboot and you should enter your new expanded environment.
No change of the partition's UUID and no need for editing /etc/fstab.
If the system was working (albeit cramped) prior to performing this, I would install Timeshift and take a full snapshot stored preferably externally, and once the operation is successfully completed I would replace that with a new full snapshot.