My Mac will not allow me to do IOS 26 update for my iPad 8 generation. It say "up to date 18.7.6" The mac is old with Monterey as latest version. iPad is unable to do update on its own because as much storage I can possibly remove, it still does not have 15 required.
iPad, iPadOS 18
Are you certain that this is an 8th generation iPad? According to Apple, the 8th generation iPad is compatible with iPadOS 26, although it is the oldest "plain" iPad that is.
iPad models compatible with iPadOS 26 - Apple Support
If you are sure that it is an 8th generation iPad, then you may need to find a way to remove more data from the iPad, even if this means transferring some of it to a computer (for archiving) – or the more drastic step of backing up the Pad, erasing it, upgrading iPadOS, and then attempting to restore the backup.
As far as the Mac being on Monterey goes, I doubt if that would be the issue.
High Sierra is theoretically enough to let a Mac sync with the latest, M5-based, iPad Pros – iPads which shipped with iPadOS 26. (See the Technical Specifications for those iPads.). I've occasionally seen posts about people having trouble using High Sierra to manage iPhones running iOS 17 or 18, but haven't seem similar posts about problems doing Finder-based synchronization and management with Catalina or later.
Update iPad via mac
