Premiere Pro natively renders video previews in 1080p, is there a way to render them in 4k ?
Previews are rendered at the resolution specified in your sequence settings, and the default is for the preview to match the format of the timeline.
So a 1920x1080 timeline makes previews at 1920x1080. The easiest way to get 4k previews is to work in a 4k timeline. I suppose you could setup a 1080 timeline to make UHD previews, but I can't imagine why. If you want to make an HD video into UHD, there are probably better ways.
Change the preview codec to e.g. cineform.
Well here for instance I work in a 4k sequence but the video preview settings do not allow me to set them at more than 1080...
Ah okay I found the solution, I had to change the editing mode to "Custom" in order to change the codec in order to change the dimensions
Thank you. THIS is the answer to the original question.