How early frigates acquired familiar cruising roles

Were early frigates already used for trade protection, scouting, convoy work, and blockade?

Mostly, but early usage was fluid because frigate could still describe a fast construction style applied to ships of very different sizes.

Trade protection, scouting, convoy work, and blockade all suited the speed and maneuverability associated with frigate-built vessels. The label was not yet confined to the later small cruising warship, however. Dutch examples could range from relatively large ships to compact 40-gun vessels, while a ship intended for the line might also use frigate-style construction. This distinction helps separate a vessel's hull form from the mission later attached to the word frigate.