In some novels, the 'power up through sex' idea can be a way to show the character's transformation. Maybe a previously weak character becomes more confident or gains a new perspective after a sexual experience. But this is more of a psychological change and not really a super - power type of gain. It can also be a complex way to add layers to the character's development and the overall plot.
The idea might also be used to explore taboos and push boundaries in literature. By presenting the concept of power up through sex, the author can make the reader think about different ways power can be obtained and the role of sex in society. But it also runs the risk of being too sensational and losing the deeper meaning of the story.
One implication could be the exploration of power dynamics in relationships. If a character is said to gain power through sex, it might show how relationships can be unequal, with one person using sex as a means to gain control or influence. However, this can also be a very controversial and potentially misogynistic concept if not handled carefully in the novel.