Can you turn automatic headlights off on a 1998 Chevrolet blazer?

No, a 1998 Chevrolet Blazer does not have an option to turn off automatic headlights. The system is likely controlled by a light sensor, and therefore, always operates automatically based on ambient light levels. You can't disable the automatic function itself. You can only turn the headlights off by switching the headlight switch to the "off" position, but they'll automatically turn back on when the light sensor detects low light conditions.