It is annoying to change the font size of equations in a LibreOffice document when you have to do it for a lot of equations because they are not affected by the size of the text. One way of doing this is with the macro below (I got it from superuser.com/questions/290197/how-to-change-the-font-of-all-equations-in-libreoffice-writer).
Sub FormulaFontSizeChanger f = InputBox("New font size:", "BaseFontHeight", 9) o = ThisComponent.getEmbeddedObjects() For i = 0 to o.count-1 if (not IsNull(o(i))) and (not IsNull(o(i).Model)) then o(i).Model.BaseFontHeight = f o(i).Component.BaseFontHeight = f o(i).ExtendedControlOverEmbeddedObject.update() endif Next i End Sub
To use it on LibreOffice Writer go to menu Tools → Macro → Organize Macros → LibreOffice Basic. Then, click Organizer and New... Paste the code above and save. Your macro is created. Now, menu Tools → Macro → Run Macro and find it.