Right now, I've figured out how to apply a discount at checkout for an entire collection. This is great and all; however, it doesn't showcase the discounted price on the item page. What I can (and could) do is go and manually go and set the compare price/actual listing price for every single item and variant, but there are just so many items I want to put on sale, it just seems like it would be super laborious.
Is there a way to better go around doing this similar to that of applying a discount at checkout for an entire collection?
If you want to put a collection of products on sale, you will definitely want to utilize the product pricing features as opposed to a discount code. You can make the changes in bulk fairly easily.
From your products list page in your admin, click on the 'more filters' button. From there, select the 'collections' filter and then choose the collection you want to edit. This will show all the products that belong in that collection. Now we will want to use the bulk editor to make bulk changes to the 'compare at price' and/or 'price' fields. In order to do so, click on the checkbox to select all products and then select 'edit products':
From there you can fill in the prices to your needs. You can even click on a product then press shift + click on another product/variant to highlight all of those products at once to make universal product changes much faster.
If there is anything else I can help you with, please let me know.