In her previous life, how Empress Yuanzhen managed to surpass the Core Formation heavenly tribulation, Yan Yu was not clear.
But one thing is certain, the current Zhao Yuanzhen, in terms of temperament, definitely doesn't match up to Empress Yuanzhen from her past life—after all, she was wanted by the Lu Country for several years, constantly fleeing to avoid pursuit, living every day on edge like a stray dog.
To endure until Core Formation in such harsh conditions requires either extraordinarily strong willpower or an extremely abnormal mindset. According to Yan Yu's recollections, Empress Yuanzhen possessed both, so it's not surprising that she could withstand the heavenly tribulation.