You litterally have to go to Paramount+ (or any streaming service, it is all the same answer) in your web browser, go to the show, start playing an episode. That will give you the link you need to put into the .strmlnk file.
Yes, it is that manual and tedious.
No, there is no easier way to do it or any tool that is going to do it for you.
No, no one has a giant, up-to-date repository that you can just grab what you need from it.
Yes, it takes forever, but is totally worthwhile if you want all your media in one place like I do.
Yes, with new shows you will have to keep this up, so every week with Star Trek you have to create an additional Streamlink. I recommend using Justwatch to keep track of what is new and when so you know when to create a new Streamlink.
No, it will not update automatically if it moves to another service; you have to do this all over again.