I've just tried this, and if before buying, you click on the postage details on the listing, that is, click on See details, it brings you to the page where it shows the service that seller is using for the item.
I know that some options are not available on the app or mobile browser which I do not use, but it's certainly there when using a laptop / PC/ desktop . Use Chrome or Firefox they work best with eBay.
@liba_4619