As an existing user of Adobe Photoshop Elements you are eligible for the upgrade pricing for Photoshop Elements 2021 & Premiere Elements 2021 if you buy it as a direct download from Adobe.
Normally this would be $119.99 (as opposed to $149.99). However, there is currently a limited-time deal on the Adobe US website which will give you 33% off, bringing it down to only $99.99. This is available until 27th June 2021 and because it's a special deal, it's the same price for both new & existing users.
I did so some weeks ago and it worked perfectly well. You can also upgrade Photoshop Elements alone, without Photoshop Premiere Elements; in this case there is probably no special deal. If you want the best Photoshop, really different from Photoshop Elements 19 or 21, you have to purchase "Adobe Photosop 21", but this Edition is very expensive --+-10$/monthly!! You can try it for free 7 days!!
The same deal includes the stand-alone Adobe Photoshop Elements 2021 at 30% off for $69.99 🙂
And bigger doesn't always mean better when you're talking about Photoshop 🙂 A lot of Photoshop Elements users appreciate the more simplified approach that Elements takes, as well as all the extra help and Guided Edits that Elements offers. And don't forget the Organizer which makes managing all your digital images and videos a breeze (most of the time 😉 ) - a feature notably absent from Photoshop.