The tradition of blessing a person to live to 120 years, as a way of wishing someone long life, only began in the last few hundred years. The term ad me’ah ve’esrim appears in responsa literature from the eighteenth century through the present; there is no evidence of the phrase being used in earlier times.
Ari Z. Zivotofsky, “What’s the Truth About . . . ‘Ad Me’ah Ve’esrim Shanah‘?”, Jewish Action (Summer 5780/2020), 72.