How to make fixed line spacing function work?

I am using LibreOffice 5.2.2.2 on a windows 10 laptop. I tried adjusting fixed line spacing to get a look I want but it just did not work no matter how large I set fixed line spacing to (from 0.1 cm to 10 cm). I tried clean direct formatting, and it did not make fixed line spacing work. Single or double line spacing worked, though it won’t help if I use Chinese and English characters in one paragraph. They have different definition of “single line spacing”. Please help.