No matter which version of Power Apps I choose.
I am not provided the option to try the modern controls. I choose the latest, 3.23123.8, These are my options when I type modern controls.
I hope this helps you to enable modern controls in your app.
Please tick Accept as solution if the answer is useful.
Thanks,
The Modern Controls toggle is currently available on the General setting tab - I think they moved it
Hope that helps,
Bryan