Some may have a single hex screw holding it’s handle in place. If the faucet has two knobs each knob may be held in place with a Phillips head screw.
But a flat head screw? Maybe to pry a cover off something, but for that you could just use a butter knife. Flat head screws are more commonly used on electrical faceplates and barely anywhere else.
A faucet assembly contains nearly no screws.
Some may have a single hex screw holding it’s handle in place. If the faucet has two knobs each knob may be held in place with a Phillips head screw.
But a flat head screw? Maybe to pry a cover off something, but for that you could just use a butter knife. Flat head screws are more commonly used on electrical faceplates and barely anywhere else.