I shoot in raw and edit with Lightroom. What settings, such as resolution and aspect ratio, should I use to export JPEGs for presentation using an Epson EH-TW5210 Full HD 1080p, 1920 x 1080, 16:9 projector?
I agree with @xiota regarding the compression settings. For the resolution, you have several options.
Export and crop at 1920x1080
Crop and maintain the proportion of the original photo. For a 3:2 ratio, you can use (1080/2)x3 = 1620x1080. For a 4:3 ratio, 1440x1080.
Crop similarly for portrait orientation. For a 2:3 ratio, 720x1080. For a 3:4 ratio, 810x1080.
Rotate your projector for a vertical format.
Do whatever you want and let the presentation software resample your images.
Personally, I would edit and export normally, then let the presentation software handle resizing for display. After editing, I often export full-resolution, progressive JPEGs at 100% quality with no chroma subsampling.
I retain the original raws and JPEGs, and the difference between high-quality JPEG and lossless is negligible. The result is more than good enough to use as a base for further crops and conversions for other purposes, such as online galleries or printing.
These files tend to be large and may load slowly. If you find this to be the case and your images will not be used for any other purpose, there is no advantage to saving at a size larger than what your projector can handle.
If having black bars along the edges because of aspect-ratio differences is unacceptable, most editors now have aspect-ratio crop. Select the aspect ratio that corresponds to your projector.