A DCP-Digital Cinema Package is a folder with a collection of specialized files. With Davinci Resolve Studio, you can export a DCP for playback in theatres that support the DCI standard DCP files.
Your Resolve project (timeline) should be at one of the 2k DCP aspect ratio and resolutions 2k DCI Full (1.9), 2K DCI Flat (1.85), 2k DCI Scope (2.35), not full is simply called 2k DCI
Most theatres are still 2k, not 4k, so at this point it is not super useful to create a 4k DCP
see here for more info on the DCP format on
https://en.wikipedia.org/wiki/Digital_Cinema_PackageSupported Aspect ratios for DCP with Kakuda, Resolves included DCP creator
If your film is not one of these ratios, it must be either letterboxed or pillarboxed within one of these ratios. Use output blanking to crop to make to a specific ratio if needed, under the Timeline menu option, 2nd last option. This will mask your video to this ratio
