Quotes allow you to group items together, but the group titles are small and on the first line of the quote table.
The 'Group Title' we output isn't a specific element that Word can understand or interpret as a group title. Word has no concept of groups within tables or headings for these groups - you can only apply styling to Word tables for the entire table heading and footer rows, first row, first column, and then odd/even rows.
When you add groupings to a quote in CRM, the output to Word simply generates a new row, puts the group title in the first column of the table and ignores the rest of the columns in that row.
Firstly this means there is a bug which means you cannot modify the font size of the group title in isolation.
Secondly, having the group title on the first cell of the table is not a great place to put it, can easily be missed and means you are limited by characters (before multiple rows are taken up needlessly). A better positioning would be just before the table.
Summary: Please allow font size and positioning of the Group Titles in Quote Tables!