How do I change the part after the domain (example: xxxxx.com/collections) in the Dawn theme.
As far as I know, the built in paths like /collections, /products, etc cannot be changed.
If you really want to change this, you can use url redirects (Online Store → Navigation → URL redirect). This way even if someone were to visit domain.com/whateveryouwant, you can redirect them to domain.com/collections, so there’s at least an outward appearance of having that new path.
But if you have a large number of paths that use “collections” as a root (ex: domain.com/collections/col1, domain.com/collections/col2, domain.com/collections/col3, etc), then you have to create these redirects individually, because the shopify redirects tool supports wildcards, last I checked.
Alternatively, you can check out some redirect apps that may be better for handling bulk redirects: https://apps.shopify.com/categories/marketing-and-conversion-search-engine-optimization-page-redirect
Hope this helps.