Update LR4 to highest non-cloud version still possible?

Here are the "official" instructions from Adobe on how to purchase Lightroom 6:

Download and install Lightroom 6 (Single App license)

As far as I know, this link is still valid. It will enable you to purchase Lightroom 6 which is the last version of Lightroom which was a standalone version. After you download and install, you will be able to install the 6.14 update. That was the final update and there will be no more updates, no more upgrades. It is end-of-life software that will never be updated or upgraded again.

Indicate that you want to purchase an upgrade version, and the price will change.

Adobe Checkout

Take note that there have been numerous cameras that have been released since Lightroom 6 support ceased. If you have one of those newer cameras then it will still be necessary for you to use the standalone DNG converter to convert the raw files in order to work with them in Lightroom 6.

As I indicated, "I believe" that link is still valid. I haven't tried it because I don't use Lightroom 6. I subscribe to the Creative Cloud and have no experience with Lightroom 6 whatsoever.