In impredicative MTTs like UTT (Luo 1994), there is the internal totality Prop of all logical propositions and we can define all of the other logical operators by means of ∀.
Here are the definitions of the logical operators by means of ∀ (a special case of Π) in an impredicative type theory (see, for example, section 5.1 of Luo (1994)).
3.138.110.119