By accident, she transmigrates into the revered empress dowager of a fictional dynasty. Even the emperor, who has the final say in everything, treats her with respect and filial devotion. What a comfortable life!
Empress Dowager: Who is that young lady over there?
Palace maid: The second daughter of the Minister of Justice.
Transmigrated woman: To win a man's heart, the mother-in-law relationship is the most important thing. The empress dowager has noticed me! She's looking at me!
Empress Dowager: Such a pretty face. A pleasure to look at. She'd be perfect for serving the Buddha.
Transmigrated woman: ???
Empress Dowager: Who's that playing the qin in the imperial garden?
Palace maid: Your Majesty, that's Noble Lady Xue.
Empress Dowager: Such lovely hands. What a pity not to put them to use copying texts.
Reborn Noble Lady Xue: ???
*Fictional history with lots of original worldbuilding. Feel free to drop it if it's not your thing.
*The heroine isn't an old granny, and is at most around thirty.
*I'm not good at history, and the dynasties are a mash-up. There's really no need to scrutinize it.
*A silly little palace-intrigue story. Please don't bash it if it's not your thing. Let's part on good terms.
Theme: After the former palace-intrigue champion retires