WordPress plugin have a activation method, It’s very useful, and we can use it for various things.
One of the popular method in plugin, is “Activation Redirect”, this is a method used by a lot ( I mean **A LOT**) of popular plugins to redirect user to plugin settings page, setup page, or even plugin about page (of course, within the admin panel) when user activate plugin.
This is (probably) useful for user on-boarding purpose, annoy user, keep the user inform about the feature of the plugin or help them setup the pages required by the plugin or install additional plugins/add-on.
Note: I actually really hate it when plugin/theme author did this. But in some case it could be useful.
Usually plugin use register_activation_hook() function to do this. But theme don’t have similar method/function. However, there’s a workaround for that.