You can paste in non-breaking space characters from the clipboard. The Unity editor's input fields don't allow you enter a non-breaking space with the key combination Alt +0160, which is a fairly standard way of adding characters by their Unicode values on Windows. Alt+Space may work on Macs. Alternatively. if you're using TextMesh Pro you can use a <space> tag to represent a non-breaking space, such as in "un bouquet de fleurs<space=0.5em>?"