No. While 'Reign' is based on a true story, it takes many liberties for the sake of drama. It's a fictionalized account of Mary, Queen of Scots' reign, so not all events are portrayed exactly as they happened in history.
Charles Oliveira was a Brazilian kickboxing and mixed martial arts athlete. On May 16, 2021, he defeated Michael Chan in UFC262 and became the new UFC lightweight champion. On December 14, 2021, at UFC269, he successfully defended his lightweight belt. However, on May 8, 2022, in UFC274, he was unable to win the lightweight title due to his weight. Oliveira had a 28 - 8 - 1 inconclusive record in his career, defeating top players such as Tony Ferguson, Kevin Lee, and Michael Chan. He was seen as the image of a low-class person who had made a comeback. After years of hard work, he finally became the UFC champion.
The reign of the king appeared in the first episode of the anime, Little Fox Demon Matchmaker.
While waiting for the TV series, you can also click on the link below to read the original work of " Little Fox Demon Matchmaker " to understand the plot in advance!
In my opinion, 'Reign on Me' isn't a true story. It likely combines imaginative elements to craft an engaging narrative rather than being a direct account of real-life events. Maybe there are some common themes or emotions that can be related to real life, but not the entire story.