If you're just interested in buying whatever is going to get listed into big exchanges, then the easiest way would be to follow exchanges on Twitter and also their Telegram. Usually, announcements are made a few days before the listing happens.
Even if you follow exchanges, then you are still too late because when a large exchange announces that it is going to list a certain coin, the coin pumps instantly. Buying in after the announcement is pure gambling because there have been enough coins that after their announcement pump kept doing down.
What you can do is look at the type of coins an exchange prefers to list, and then compile a list of potential listing candidates, and take a position in them beforehand. It's still somewhat gambling, but less so than blindly buying into a pump where you don't know what will happen afterwards. It's more of a calculated guess.
A hint is that some of the coins that will be listed, show increased price activity (i.e. insider traders taking positions) before the listing announcement.