Do you know any yaoi manga where the seme is a child but the uke waited for him... Like Sa...

https://www.mangago.me/read-manga/a_paramour/

This one you talking about?

God that shit was isnae, sayonara alpha gave me goosebumps

Mn... I already read that

If you like sayonara alpha then you must try this one by same mangaka--
https://www.mangago.me/read-manga/shingeki_no_kyojin_dj_ore_no_alpha/

For future save this one as well -
https://www.mangago.me/read-manga/otogibanashi_wa_jigoku_no_hate/

https://www.mangago.me/read-manga/yoake_no_uta/