Can I use Apple TV with a Dell Monitor Dell UltraSharp 49 Curved Monitor - U4919DW?

Apple TV expects to output a 16:9 image over HDMI. 32:9 is way different, even wider than cinema (~21:9). It is up to the monitor how that is handled. Any optional subtitles have a fixed position in the 16:9 frame, so those might disappear if the image is scaled too much.

That monitor appears to have no speakers, so you’ll probably have to connect bluetooth speaker/headphone to Apple TV directly.

It doesn’t seem like a good solution for this purpose, but I suppose you could do it.