Philomel the Fake (2020)

Blurb:
After finding a mysterious book in the imperial garden, Princess Philomel not only discovers that the book’s villain shares her name, but that other events in the story are coming true too. Now, she believes that she’s an imposter and that the real princess will take her rightful place, leading to the execution of Philomel the Fake! So to avoid a tragic death, she has to make sure the rest of the book doesn’t come true. Can this fake princess change what’s already been written?

Source: www.anisearch.com/manga/63438