Zhao Pan'er from 'A Dream of Splendor' and Zhen Huan from 'Empresses in the Palace/ The Legend of Concubine Zhen Huan' and Minglan from ' The Story of Minglan'. I am a long time fan of The story of Yanxi Palace, it is my favorite drama of all time so naturally I have been searching desperately for anything that can even slightly compare ever since first watching it.
As for 'A Dream of Splendor' I am just over halfway through and I am loving it. It has a very different storyline compared to Yanxi Palace but the the female lead is giving Wei Yinglou energy! She is so smart but doesn't show all of her cards until she needs to, she doesn't take bs from anyone.
Zhen Huan is a bit more similar to Yanxi Palace in that is is a palace drama. Her slow journey to the top, the scheming in the harem, and once again she is smart. She learns fairly quickly how to adapt to harem life and she slowly becomes colder and more decisive and calculating. The saga that she goes through makes her more and more like Yinglou and that was one of my favorite things about her.
Of course everyone recommends 'The Story of Minglan' when people ask for Yanxi Palace comps, and they aren't wrong. This is also a good show. Minglan is definitely a strong character who is very capable and will get things done. And her growth is beautiful and heartbraking so that of course reminds me of Yinglou and her perseverance.
I hope you can find something you like from these!