toolbar across top too small for me to clearly read
It seems you may be referring to the menu bar. In Linux Mint, I can adjust the system
default font. This of course will affect more than just the menu as well as other applications.
I am referring to the LibreOffice toolbar - I do not know Linux Mint - or even what that is. I have found several sets of instructions for enlarging the toolbar font - they work in Libreoffice 5.2 but Do Not work in Libreoffice 6.2. I have 6.2 and so does my husband who is having great difficulty reading the toolbar at all.
Linux Mint is an operating system like Windows or Mac OSX. The change I mentioned does also change most of the font in toolbars. The exception here is when using the Tabbed ‘ribbon’ toolbar not all text conforms to the change.
Seems like duplicate: Type size in menu bar and drop down menus
There are numerous duplicate questions on this site.