Is the Messenger's - may Allah's peace and blessings be upon him - actions and sayings before prophethood considered Sunnah?

The actions of the Prophet, may God bless him and grant him peace, before his prophethood, do not obligate us to follow them, except for what his law later prescribed as permissible; because it then became a law for us. Sheikh Al-Islam Ibn Taymiyyah emphasizes that matters before prophethood are not mentioned for legislation, unlike his actions after it, and that Muslims have unanimously agreed that whatever was enjoined upon the servants came after prophethood. Therefore, whoever emulates his actions before prophethood, such as worshipping in the cave of Hira, and abandons the prescribed acts of worship commanded after prophethood, is mistaken. The Muhaddithun (Hadith scholars) are keen to mention everything reported about him, may God bless him and grant him peace, even if it was before his prophethood, and it falls within their definition of Sunnah.