There are two interfaces to display devices, spi and the purpose built ribbon cable connector.
Documentation with respect to the chip sets for each display device should first be sought. The drivers for display devices must provide an interface to registers for the supported resolution(s). A register to select a given (supported) resolution, the software you will need to write must be based upon the timing of the scan for each line of pixels across the screen plus the number of lines of pixels down completing the screen resolution of native pixels. Check out the YouTube channel belonging to Ben Eater. It will be easier to subscribe to his channel then search for his marvellous video tutorials of how to build your own "The worst video card" utilizing breadboards, prototyping wires, basic IC counter chips, a 10MHz regulated crystal in a can, a handful of LEDs to serve as indicators, assorted resistors, a few capacitors, plus a few other digital functions each packaged in one of several different package types. This is a complete functional deconstruction that is rebuilt in stages showing basic digital circuit testing methodologies as each stage is then integrated with the prior tested stages until you will load an image file onto a memory card and the "static" data will be successfully displayed on a (chosen) display device. This practical exercise by Ben Eater together with his website will have you answer all your questons and prompt you to ask several extra questions that will open all the software references to solutions you will need to complete this interesting project of yours. I have learned from the example by Ben Eater how important it is to break down a problem into manageable pieces where the observable test data is brought within measurable ranges. Digital electronics is in fact a precise environment where functional problems can be solved in this manner. It is important to build confidence with an introductory framework such as Bens coincidentally relevant video card build. I find it has brought a sharp sense of mental focus from which I am able to see the next step for my own projects. I hope this helps?