Calc chart - how to change size of equation box?

I want to change the size of an equation box in a chart. However, I can’t grab any of the grab-handles. Chart only allows me to reposition the box.

If I right click on the equation box, the Size option is greyed out.

(Note that I don’t have these problems with the legend box.)

Thanks,
Don C.

@dculp ,
In order to be able to help you, we need to know your operating system and the LibreOffice version (four-digit, e.g. 7.4.5.1).
Please also state the file type in which you have saved your file.

Please upload a reduced and anonymized file here so that someone can examine it.

Thanks.

Windows 10 Pro
LibreOffice 7.0.6.2
File saved as ods
See attached minimized file (Chart_question_1a.ods)
Chart_question_1a.ods (32.0 KB)
.

And by changing the font size, you will not get the desired change in the size of the equation box?
image

I want to keep the current font size.

I want to increase the vertical size of the box to increase the vertical spacing between the f(x) line of text and the R line of text. (This can be done with the legend box.)