Avoid Big Sur Update But Still Install Others?

Hi guys - what is the best method to avoid the Big Sur update but still install the other smaller updates that I have still to do for Safari and Catalina etc? It seems that when I press in to "other updates are available" here:

and tick those:

and press install now, that it's going to install Big Sur as well still as it greys that one out when it returns back to the first screenshot as though it's including that too, so I cancel it beforehand concerned it will commence the Big Sur one as well?

Thanks for your help.

Edd