Nope - Gōngzhǔ 公主 is a first rank princess strictly reserved for daughters of an emperor - there is a high…
I think Lejun is the daughter of the late emperor. Since Li mao and her are supposed to be full siblings and it's mentioned in in ep 4 when Yunzhao is talking to xie huaigui after the events that happened on yaoyao's wedding night.
Guys someone explain why Lejun is titled 'Xianzhu' and not 'Gongzhu'. She is supposed to be the daughter of late emperor and should be in fact titled gongzhu. And same with Yunzhang (yaoyao's mother). She addressed Empress Wenxi as sister-in-law which means she was the sister of the empress and should be titled 'Zhang gong zhu' and not junzhu.