Known. The tombs were built with rooms, doors, and windows, like a house.
Three tombs were found in Rizhao, in Shandong province, on China's east coast, about 650 kilometres southeast of Beijing. They are about 1,800 years old, from the Han dynasty. Two of them carry the family name Huan. One tomb has two rooms joined by a doorway, with small wooden doors and windows. About 70 objects were found, including an iron sword, bronze mirrors, and a lot of pottery. A wooden carriage for a coffin was found as well. Two of the tombs had been robbed. The third was still full.
The page does not say what is still argued.
https://www.ancient-origins.net/news-history-archaeology/chinese-family-tomb-0020808