I tend to be skeptical of lists that try to pin down 'top' themes in femdom, because what's popular on, say, TikTok for quick-read romance might be totally different from what's circulating in dedicated kink communities. The stuff that blows up often plays with power dynamics in a very accessible, almost fantasy-fulfillment way. You see a ton of the 'CEO/boss lady and her personal assistant' setup—it's a clear container for the dynamic, with built-in stakes.
A theme I see everywhere now is the 'service submission' focus, less about impact play and more about the male lead proving devotion through acts. Think 'The Ritual' by Shantel Tessier vibes but flipped. The emotional core is often the domme's vulnerability masked as control, and the sub's journey to earn her trust. It's less 'punishment' and more 'guided transformation'.
Honestly, a lot of the most popular plots now blend femdom with other romance tropes like marriage of convenience or fake dating. The power exchange becomes the twist on a familiar structure, which makes it easier for new readers to dive in without feeling overwhelmed by heavy BDSM terminology.