When I want to look at available versions for a given package on a mirror, another method to get an overview quickly is by running
apt-cache madison <package name>
This will search the local package lists (so make sure you’re apt update'd) for all versions of the given package (and print the mirrors on which that version was found, if multiple are configured).
Note that
Unlike the original madison, it can only display information for the architecture for which APT has retrieved package lists (APT::Architecture).
(Actually downloading the .deb then still requires to either manually craft the URL or by reading it from the Packages file - or tell apt to install it for you )