I'd like to know if there's any code I can incorporate into my store that allows products that are out of stock to be at the bottom of my collections page, showing my customers the products that are in stock first
Sorting either types on the frontend without the support of apps is an advanced theme customization.
If you need this automation setup or customization created for you then contact me directly by mail for services. Please always provide context, examples: store url, theme name, post url(s) , or any further detail. Contact Info in signature.