Khmer is a complex script. Unlike English, where letters sit in a line, Khmer letters often stack on top of each other (consonant clusters) and require specific "subscript" characters.
If you need fonts for historical preservation (e.g., reproducing stone inscriptions from Angkor), standard Unicode fonts won't work. You need specialized supplemental fonts like: khmer supplemental fonts
When looking for the best supplemental options, these widely-used families are highly recommended by experts and the Khmer Software Initiative : Khmer is a complex script
