If the son's room is bigger than his parents' room, it may have some influence from the perspective of geomantic omen. The following are possible impacts:
1. Family disharmony: If the son's room is larger than the parents' room, parents may feel neglected or excluded, resulting in disharmony in family relations.
2. Decline in family fortune: If the son's room is bigger than the parents' room, parents may feel that their fortune has been affected, which may lead to a decline in family fortune.
3. The family fortune is damaged: If the son's room is bigger than the parents' room, it may make parents feel that their fortune is affected, which will lead to the family fortune being damaged.
4. Family health problems: If the son's room is bigger than the parents' room, parents may feel that their health is affected, which may lead to family health problems.
In a word, Feng Shui is a traditional China culture, which emphasizes the relationship and wealth of family members. If your son's room size conflicts with his parents, I suggest you communicate with the Feng Shui master and learn more about Feng Shui.