Xianle Quartet is a top tier polyship not only because of the metric ton of emotional baggage (and the sheer volume of sexual tension and awakening possible between 3 virgins and an effectively celibate fertility god), but also simply because they're all from a country renowned for beauty and pretentiousness, therefore treating impossible beauty standards as the norm.
Xie Lian's canon internal thoughts consist of not infrequently calling people ugly. Can we blame him? He was raised constantly surrounded by and continues to surround himself with devastatingly attractive people. Feng Xin, canonically olive-skinned and handsome, archer's figure. Mu Qing, canonically delicate-appearing and pretty. Hua Cheng, growing up to be tall and savagely beautiful.
Meanwhile, Hua Cheng is a literal fashionista, decked out in every possible silver accessory at any given moment, jingling like a Christmas elf and fabulous while doing it. He throws money around on luxury items just because he can, and his taste is impeccable. Mu Qing straight up destroys his own statues if they're ugly, literally described as wearing luxurious robes that he probably made himself because no one could do it better. They're the divas of this operation. They're judging you, hard, and they want you to know it, so you will.
Xie Lian is the equivalent of the naturally beautiful friend who doesn't wash their face with anything but a bar of soap and comes out looking flawless. He needs absolutely zero fashion sense because he could wear a trash bag and people would think it looks high fashion. Feng Xin is the himbo friend who washes with 10-in-1, yet his skin glistens in the sun like an oiled up ancient greek olympian. He does a normal amount of working out and comes out shaped like Captain America. They're simply God's Favorite, so they don't need to try.
Basically, I picture them as the blindingly hot polycule walking around like the Cullens entering their high-school cafeteria. Hair blowing in an invisible wind. Throwing incredible amounts of shade in the communication array.
They're hot. They're judgmental. They're literally the Mean Girls.