I want to visit my parents who work in China and ask for S2 visa. I am confused about the

I am confused about the maximum intended stay allowed per one entry for S2. I have read that it is 180 days, however I am not sure whether it is possible to get visa with single entry for that long? My desired length of stay is 97 days. I am not sure whether to put a lower number of days on the application and then extend my stay once I am in China, or just state the longest intended stay in China as 97 days. Thank you!