To begin with, I recommend that you read this article https://fireart.studio/blog/product-design-vs-ux-design/ . With its help, you can learn a lot of new things for yourself on the topic of design. By the way, you can contact the Fireart studio for advice. There they will definitely be able to answer your questions and tell you about the prices for the services that you need. I myself turned to them when I was making the site, and I can say that they do the work at a very high level.