Question

how does the resistance change as you add bulbs to a series circuit

Answer 1

IF THE BULBS ARE CONNECTED IN A SERIES THEN RESISTANCE INCREASES STEADILY BECAUSE OF HEAT PRODUCED BY BULBS

Answer 2

Bulb acts as a resistor in a circuit.
So, if yoy add bulbs in series, it will be equivalent to resistors in series.
And in series resistance adds up.
So the net resistance will increase.