A Mac Pro from 2010 has the potential to upgrade to either macOS Mojave 10.14 or macOS Catalina 10.15.
It can only do this if the graphics card that is installed uses the 'Metal' API.
To find out if your Mac Pro has a 'Metal' capable graphics card click on the top left of your screen
click on About This mac and then on System Report.
In the next screen click on Graphics/ Displays under Hardware to see if your graphics card supports 'Metal'.
If you are interested in upgrading your Mac Pro you can buy a suitable graphics card if you have a few hundred
$'s or £'s or €'s spare.
Install macOS 10.14 Mojave on Mac Pro (Mid 2010) and Mac Pro (Mid 2012) - Apple Support
Oh and I forgot to add that yes pressing and holding the Shift key down will boot your
mac into Safe Mode.