Hello Anna,
Your message is a bit unclear however assuming you meant how to make immersive reader AVAILABLE you can do so through the following steps below:
1)Open your Word document.
2)Select the View tab, then select Immersive Reader Icon for Immersive Reader . Immersive Reader will launch a full screen experience.
3)Choose the Immersive Reader options that work for you from the ribbon.
4)Once you click in your Word document to read or edit, the Immersive Reader ribbon will minimize. To make the ribbon visible so you can change Immersive Reader settings or close Immersive Reader, select the ... at the top of the screen.
These steps was referenced and taken from the following source and should you have further concerns please visit: https://support.microsoft.com/office/a857949f-c91e-4c97-977c-a4efcaf9b3c1
If this hasn't addressed your concern/problem and you'd like to ask further please do not hesitate to contact me again.
Thanks,
Parth P.