Enabling this option will push the compose window to the center of your inbox, expanded across the majority of the screen for a better viewing experience.
Google launched a brand new compose a few months ago, which gave users a bevy of new tools to build out their emails, as well as a new design to let you open a compose window without ever leaving the inbox. However, it appears that some users enjoy a more full-screen compose experience, not unlike the Gmail compose of Yore.
By default, the formatting toolbar will stay on in the full-screen compose.
Users can switch to full screen by clicking the expand button in the top right window or set full-screen as the default by selecting the “Default to full screen” option in settings.
If you don’t see full-screen compose functionality just yet, have no fear. According to the Gmail team, it’ll be up and running for all users over the next couple of days.