Interface mock up designs

I am a CEO that wants to convey my application ideas to my internal dev team with well-thought-out working mock ups to aid their product development process. I want to be able to work with a talented designer that can run with my sketches and expand the sketches considering all the latest user experience protocols and fashions. I would like to work with a designer that starts to understand our products that will then aid faster turnaround of concepts etc in the future. We are using Figma and have a library of designs at present. However, this project will look at improving these legacy designs as well.