Comment 1 for bug 1675825

I set default line spacing units to percents and this works for me. Click on the Text tool when nothing is selected and then set line spacing to e.g. 150%. After that when you'll create a new text your line spacing will be dependent on font size you select.

Percents, 'em' and 'ex' are "relative" units which depend on font size, other units like 'pt', 'mm', 'px' are "absolute" so line height has absolute value which doesn't change with font size.