I want to create a desktop background for my PC.The native screen resoultion is 2560x1440, so I thought I would crop a higher resolution image to that exact size. How do I do this in Lightroom CC? I can see how to crop to the 16:9 aspect ratio, but 1920x1080 seems to be the only defined option. I see how to resize the 16:9 crop but it seems to be guesswork as to the resolution of the cropped inage.
While it isn't obvious, cropping to exact dimensions is a two-step process much like it was in traditional Lightroom and Lightroom Classic.
1. Make the image the correct ratio as you have already done by cropping it to the aspect of your finished image.
2. Export the finished crop to a specific size using the Share icon and then selecting the Save As... option. In the Save As dialog, at the bottom use the pulldown to select Custom and enter the desired long edge for your cropped image.
At this time there isn't a place to set more options like Resolution. Perhaps in a future version?