Maximizing the viewing space is a big thing for all users in any application. These days, almost all application give us the option to hide "Title bar" then Why not in LibreOffice too.
Right now we need to depend upon third-party tweaks just to 'hide title bar'. As in the screenshot given below:
Steps to Reproduce:
The options is not available like Firefox and Chrome and other application to unselect or select "Show system title bars and borders".
Takes too much of screen size.
More space a user can have
User Profile Reset: Yes
The general case for Client Side Decoration "CSD" like this is WF dupe bug 113388, Gnome specific is bug 115512 where the OS/DE provides API support.
*** This bug has been marked as a duplicate of bug 113388 ***