One of these maybe?
https://www.mangago.me/read-manga/ai_to_yokubou_wa_gakuen_de/
https://www.mangago.me/read-manga/everyone_stand_up_boys_love_private_high_school/
https://www.mangago.me/read-manga/tenpure_gakuen_no_tenkousei/
https://www.mangago.me/read-manga/yarichin_bitch_club/
https://www.mangago.me/read-manga/oshioki_gakuen/ The most ridiculous but a classic
https://www.mangago.me/read-manga/the_teijo_academy/
I found it, but it’s one of those straight to English magazine releases so it’s not scanlated. Ai to Yokubou wa Atarashii Gakuen de (HANA)
It has several different titles depending on where it was released:
Lust and Love in the New Academy - Idol Edition
Yoru's Forbidden Erotic Situation
There is also another similar one here: https://www.mangago.me/read-manga/kunshu_no_ai_wa_yoru_ni_hana_saku/
It was about a school called full bloom that teach people how to have sex or something like that, it’s BL and has different couples but I forgot the name and nothing pops up when I look up full bloom