Do I have to Update when upgrading from XTool D1 10w to 20w?

You don’t need to update anything in LightBurn other than potentially your cut settings at least from the ability to use the new laser module perspective.
Some considerations:
For crosshairs, do you use them? Do you use them and does the 20W module require the same pointer offset? If not you’ll have to adjust for this
Addressable machine size. If the laser module dimensions are different and impede full motion you may need to restrict the working area of your laser in Edit->Device Settings.