Can you use plug-and-cord on a baseboard heater?
You probably could install a cord. However, you'll have to install a 10 AWG cord, and a 250V 30A plug (NEMA 6-30P). And you'll have to plug it into a 250V 30A circuit, with properly sized conductors and overcurrent protection. Unless, of course, the heater is rated to work at lower voltage/current.