20.10 to latest version KUBUNTU - How to?

Solution 1:

You are always best reading the release notes for the product you want to upgrade to.

Kubuntu's 21.04 release notes can be found at https://kubuntu.org/news/kubuntu-21-04-hirsute-hippo-released/

And that will tell you to read https://help.ubuntu.com/community/HirsuteUpgrades/Kubuntu

Any issues of concern the QA (Quality Assurance) testers found will be documented there, and along with the instructions the team QA-tested.

Blogs and even sites like this maybe easier to read, but I'd always opt for the official instructions that were QA-tested by the team themselves.