I have installed Ubuntu on old systems that were not on the officially-supported list. So, you could try the latest Ubuntu release. If it doesn't work, you can always wipe it and then install 18.04 LTS. No harm done. If you want to try out the latest Ubuntu without installing, boot your system from a Ubuntu Live USB. You can run your system from that to see if everything works and that it supports your hardware. Backup your personal files first. You might also create a full disk image of your current Windows installation, using a drive imaging app such as Macrium Reflect or Acronis. That would make it easy to return to Windows, if you decide that you don't care for Ubuntu.
Dear Sir/Mam I would like to know my Dell Vostro 5481 comes Windows 10 preinstalled with it. But moved to Windows 11 using Windows update.  As I am computer science major and wanted to shift to opensource distribution, so I would like to install Ubuntu.  I have checked the Ubuntu website that the system support Ubuntu up to 18.04 LTS after that there were no updates for this system for 20.04 or 22.04 LTS version.  So, should I install 18.04 LTS? Any other suggestion would be really helpful.
Can I install Ubuntu 22.04 LTS on my Dell Vostro 5481?