Back when I owned an XPS, one of the driver options was ‘compressed screen updates’, which only updated the part that had changed. As far as I could tell, made no difference to battery life whatsoever - turning down the screen brightness even a notch did much more.

Daily driver laptop for nearly ten years, and the part that finally failed was the CPU fan, which wasn’t easy to obtain replacement parts for, so treated myself to a new laptop entirely. Mind you, the power connection was a PoS, would have been as well keeping that on an annual reorder for how often it failed. Pretty good laptop otherwise.