The immediate vision of God surpasses the natural cognitive ability of the human soul and is therefore supernatural.
The vision of God in heaven is not something that a person could attain by their own power.
It is a supernatural gift from God—a gracious act by which God reveals Himself directly.
Even the most perfect person, with all their reason and holiness, cannot “see” God by their own nature. Only because God gives Himself is this knowledge possible.
The visio beatifica (blessed vision of God) is therefore supernatural—it surpasses everything that a person can achieve by their own strength.
Source (Latin):
Benedict XII, Constitutio dogmatica “Benedictus Deus” (January 29, 1336), in: Denzinger-Schönmetzer, DS 1001
“… this vision [of the divine essence] is a grace and gift of God, not owed to man by nature, but something added and supernatural, which corresponds solely to the divine will.”
Source (Systematic):
DS 1001 / CCC No. 1028