I always thought that was my job. I always supply contractors (or DH) with sketches and pictures of what I want. I just use graph paper or a spreadsheet grid to represent each measured wall of a room laid out where I want things and my hand drawings or magazine pics of what goes where. My measurements don’t have to be perfect, just a clear visual of the end product. I usually pick out the appliances/hardware/tile/flooring/faucets/cabinets/paint, etc. myself ahead of time. I don’t go to a contractor (or DH) until I know exactly what I’ll be asking them to do as I consider the contractor to be the last step in any reno process, the one who will execute what I’ve already decided. They have the trade skills, not necessarily the design skills.
So, if you don’t have a clear picture in your mind of the finished product, you should work with a designer first to get the room laid out and all components and finishes decided. The contractor should then be able to give you a detailed quote for all the work/time required to transform your design into reality.
For example, I posted on another thread that I used ChatGPT to produce the bunk beds I want for our cabin’s additional lower-level bedroom, and I gave DH the following approximations for the adjacent walls. He will use his CAD software to dimension these walls properly, but this is what I’d expect a GC to do if we were contracting.
(I used Google images to piece together the storage wall ^^^ from separate pictures. I’ll be painting that unit red, but the color doesn’t matter at this stage.)
ETA: Does it look like I might be anticipating grandchildren? I’m not really, but you never know. The bedroom will work just as well for adults as kids.