I spent several hours to day trying to figure out a prompt to make consistent "movie stills" on Chroma using only Positive prompts, avoiding slopped outputs and heavily artifacted images, the best I could get was this:

>aesthetic 5, imdb blu-ray still from a movie scene,imax shot, movie trailer footage, candid footage of a youtube video

Picrel were the prompt:

>aesthetic 5, imdb blu-ray still from a movie scene,imax shot, movie trailer footage, candid footage of a youtube video, featuring an attractive young woman in a red dress sitting in a wooden chair at an outdoors garden.

It is by no means perfect, you can see it even outputs youtube website screenshots (lol), but it is the closest I could get to an acceptable prompt after countless outputs. I figured if you use ANY prompt related to quality it completely slops the output, and if you use prompts related to photography techniques it gives all the attention to that and ignores the other movie style prompts.