Click the pencil icon next to the line where you want to add syllable-level timings and choose Edit line text. You can also double-click a word on the waveform to edit it.
Insert the / character between syllables to break the word (e.g. ka/ra/o/ke)
Adjust the timing of each syllable by dragging the dividers inside the word in the waveform (make sure you're in Words mode)
Preview how each syllable is highlighted independently
This feature is compatible with both Karaoke and Highlight text effects.