To be honest, coming up with this type of stuff isn't exactly rocket science.
e.g. just off the top of my head:
"Chair girls - chairs turn into living girls and go to Chair School where they train to be the best chairs possible, compete in the inter-school chairlympics, all while training to be Japan's next pop idol sensation. Sofia is one such chair girl, aspiring to adorn none other than the office of the prime minister of Japan".
It's not actually hard to come up with this stuff at this point in time. Zero "come up with that shit" effort needed. Just take some random thing from real life, turn it into a highschool setting with anthopomorphic girls, throw in a school-vs-school competition so you can rig together a plot structure with zero effort, add in "seasoning" e.g. extraneous popular elements such as they are also singing idols. While it might sound left-field if you're not familiar with mecha-musume and the whole slew of anthro-schoolgirl shows, this is actually formulaic now.
e.g. recently there was a short anime show called "Love Kome: We Love Rice" about a bunch of schoolboys who were all living embodiments of different strains of rice. The rival school was all bread related, and there was a rivalry / competition element to it, where the winners become pop idols. Basically the same formula as the horse girl one, except choose a different "thing" and the other gender. Is there really much effort "coming up" with stuff like this?
You can come up with this stuff merely by picking random nouns from the dictionary then making them anthropomorphic, then bolting on the standard plot rails: in terms of construction they're akin to those oldschool American "family" domestic sitcoms which each have their one "gimmick" to carry the show. e.g. "Alf" or "Small Wonder" or "Harry and the Hendersons" which are all of the formula "generic family + 'a secret' + nosey neighbor" (which goes right back to Bewitched and Jeannie). So for e.g. "Alf", nobody really had to come up with much of a show, they only had to come up with the gimmick then inject it into a standardized "show" container. It's similar for these types of highschool/sports-contest animes which each have their one gimmick.