RGB strips are of 2 type,
One which needs directly driving each of the color Red, Green & Blue, where 3 transistors will be used with high current power supply. The ESP module's outputs (1 for each Red, Green & Blue) either Digital (switch) or PWM (Dim) will be used to drive the transistor.
The other is digitally addressable RGB control type, where the strip can be controlled by sending control data on designated pin. High current power supply (as per Voltage (which is usually 5V DC) & Current requirements of the strip) will be connected to strip & a single output from ESP module will be connected to data-in of strip. All necessary control signals like pattern, Color, Intensity, etc. will be sent from that single output pin of ESP module.
Hope this clarifies your doubt.