Full screen button

Hello everyone,
This is my project: HUB ELLIOT GROUP - PLAYCANVAS
In order to make enjoyable on mobile too I want to make the space full screen on default it means that on mobile will be on horizontal full screen view after the loading.
This is my first choice, if is not possible I think could be good for me also in another way: putting a full screen button and the user have just to press it to make the space on fullscreen.
If there’s other better ways to do it I will glad to know it.
Thank you in advance for the help I hope my request is understandable to everyone.
Elliot