I don’t know what the official Chinese rules say, or what the common practice is outside of OGS, but I believe OGS uses 1.5 komi for “one stone” games.
The discrepancy between AGA and Chinese rules is minor. However, New Zealand rules (as implemented on this server) are quite different in not increasing komi at all for handicap stones (although there is a display bug that seems to imply that it does).
See some relevant discussion here Are There Legitimate Reasons To Choose New Zealand Over Chinese? - #6 by yebellz