Power is a major theme. The female character being the queen implies a lot of power and the ability to influence. Another theme is usually struggle, like fighting against those who oppose her rule.
One similar novel could be 'I Am the Empress in This Life'. It also has a strong female lead who rises to a position of great power. Another one might be 'My Reign in This World' which shares the theme of a dominant female character in a fictional world.
I'm not familiar with the exact characters in this novel. However, based on the title, we can assume that the 'sister' is a central figure. There could be other characters like friends, family members, or rivals. Maybe there's a love interest who either helps or hinders her path to being the 'queen' in her life. There might also be an antagonist who tries to undermine her new - found confidence and status.
I'm sorry, I haven't read this novel specifically. But generally, a title like that might imply a story where a female character, perhaps referring to another as'sister', sees herself as a powerful figure, like a queen, in her current life. It could be about her journey to assert her power, face challenges, and rise above in a world that may be full of difficulties and rivalries.