Can my mother, a Hungarian passport holder, extend her stay in Thailand by one month without leaving the country?

Hello guys. My mother would like to visit me and spend a month in Thailand. She is a Hungarian passport holder so she does not need a visa for this period of time. My question is if she changes her mind and decides to stay two months, can we extend her stay one month more without leaving Thailand that costs 1900 thb? I know this was the rule before but would like if you could confirm this rule still exists. Thank you very much for the info.