Upgrading from Mojave 10.14.3 to Mojave 10.14.6 (or at most Catalina), but not to Big Sur?

I have a MacBook Pro (early 2015) with MacOS Mojave 10.14.3, Safari 12.0.3 and XCode 10.3. The webpage I want to remote debug is opened in Safari on an iPhone SE with iOS 14.2.

The answers I got on StackOverflow suggest that I should upgrade my macOS Safari and/or my XCode version installed on my Macbook.

I see that there is a download for Safari 14.0.1 Beta 4 but it requires at least macOS Mojave 10.14.6.

From https://xcodereleases.com/, I see that my current XCode version 10.3 is the latest I can get given my MacOS Mojave version 10.14.3

So I definitely have to upgrade my MacOS version.

When I go to Preferences -> Software Updates, I see this screen:

Then if I click on "More info..." under "Other updates are available." I get this screen:

So it looks like I could upgrade to MacOS Mojave 10.14.6, which would allow me to install XCode Xcode 11.3.1 at most and also upgrade Safari to version 14

Great, but I fear that clicking on the "install now" button would also install the latest and recently released "Big Sur" because this is what i see on the Software Updates screen.

So this is my (indeed simple, but I wanted to provide more context) question: Can I make sure I upgrade to Mojave 10.14.6 only and not Big Sur from the Software Updates screen I see ?

Yes, clicking on "Install now" in the second screenshot will install only the updates listed and ticked. It will not upgrade to Big Sur.