what is not compatable with Mac OS 11

I did not chastise you. And age is NOT an excuse for your attitude.

This is a volunteer user forum. No one here works for Apple and we certainly don't get paid for this, so if you want help, I suggest you chill out and try to be a little more reasonable.

I'll start here: "MY MAC info says HIGH SEIRRA and NOT CATALINA was the 1st question".

That is not a question. It is a statement.

Your Mac is running High Sierra. WHAT IS YOUR QUESTION?

If you are trying to ask if you can run Catalina or Big Sur, that depends on exactly what model Mac you have.

Apple menu -> About This Mac tells you what system you are running.

If you are running Mac OS 10.15 Catalina, most of that software which is compatible with it is also 11.0 Big Sur compatible.

If you aren't running Catalina, you have to be wary as a lot of software is programmed in older 32 bit coding, which is not compatible with either Big Sur or Catalina.

Note 10.15.7 is a variety of Catalina not too different from 10.15, just as 11.0.1 is a variety of Big Sur not too different from 11.0.

https://roaringapps.com/ is a great website to research what is compatible with each operating system.

Backup your data before installing anything new.

New M1 Macs that shipped in 2020 add another compatibility hurdle as Apple has moved away from Intel CPUs. If you are planning on getting a new machine, be aware of that.

You are not making a whole lot of sense...

Please read this document, then try posting again: Writing an effective Apple Support Communities question