How do I improve SEO for a restaurant?

I'm completely new to SEO so please excuse me if I sound ignorant.

I've seen a lot of posts saying that I should create content including keywords. However, using Google's keyword planner I can see that some of the top results utilize hundreds of keywords, some not even remotely related to the food industry. How in the world are they getting those?

Another problem I have is with the creation of content and/or landing pages. For my competitors' websites, there's only so much space they could fit in other information without appearing cluttered. I know that my restaurant is niche enough to have a multitude of ways to stand out, but is it a good idea to break the cookie-cutter mold and start hurting our site's simplicity and organization?