Page builders can give you full design control over your store, beyond what the theme settings can do. If you're looking for a page builder for Shopify then I recommend one of these.
I'm only going to list page builders that I have experience using. That said, these are the leading apps anyway.
These both have affiliate links - if you want to support my Youtube channel you can click these links before signing up. Thank you!
I have written an article on my other blog comparing the top 3 page builders - read it here.
The leading app for creating custom landing pages in Shopify. Build pages with and easy to use drag-and-drop interface. Lots of templates to choose from. It's the most expensive app though.
A cheaper alternative to Shogun. Pagefly is great if you only need a few custom pages. They even have a free plan.