The shocking ritual of the red heifer in the Torah. Please is it true?

I just read that in the Book of Numbers in the Torah, the ashes of a red heifer were used for ritual purification from contact with death. Apparently, the ritual was so strict that anyone who came into contact with a corpse had to be purified with these ashes. Some interpretations even say that according to their tradition, people had to be ritually pure before rebuilding the Temple or acting against holy sites. Is this historically and religiously accurate?