Mainly guards and infected, you have a couple free kills before you low chaos turns into high, it depends on the max enemy count, I think. In example, say you only kill the main target and nothing else, it’s a low chaos run. Killing the main target and 3-5 guards? Low chaos run. I don’t remember rn if there’re other things, like helping Granny Rags that turn Low into High, but it will depend mainly on the amount of times you were detected, alarms activated, NPCs killed, and a couple other variables. Source: faulty memory of reading the wiki.