How to use website.com/?variable=1 in Posts?

How to use https://website.com/?variable=(number) in Posts?

For example,
Put a button in the post (https://website.com/post/),
press the button, it goes to https://website.com/post/?episode=2
press another button and it goes to https://website.com/post/?episode=99
where different page will have different things (e.g. episode) in it?

Thanks!