The VIEW menu has the viewing options (similar to Apple Pages, where you can hide/show the Inspector; or Apple Preview, hide/show TOC or thumbnails, or Safari view options).

Hiding the Sidebar, hides the library, song lists on the left panel (or click the rectangle icon top left beside the forums Globe button to hide/show).
And you can either [View menu] maximise or minimise the Player controls on the right (or click the rectangle icon top right, next to the Share button).
This means you can show the chart itself without any clutter and minimal player controls on the bottom or view what you need at the time.

(iReal Pro version 2021.8)