Hi everyone, beginner question here, I just tried the pmosfet 1.8V, and turn it on fully with 1.8V voltage source. I observe a current of around 200.7uA, My question is, why is the current so low? I have never done IC design before, only doing pcb design before, and I expected mosfet to be more or less shorted when turned on. What happens here?

You are probably confusing this with discrete transistors used on PCBs/breadboards. The reason for low current is the small W/L ratio (1um/0.15um in your case). Increasing the width to 10um will increase the current to 2mA. When |Vgs|>|vth|, the transistor is turned on but does have a resistance (1/gds) between its source and drain terminals (depending on the region in which it's operating). And smaller the size, greater will be the value of this resistance. If you want to use transistor as a switch, make sure the drain-source resistance is low (increase W/L )and the transistor is operating in triode region.

Thank you for the answer, for an additional question, what is the max value for the W/L. Say for example if I have W/L=500, is it excessive?

@Edo Jayakusuma if the W is too big you get an error from the simulator. So do some tests. If you need more you can use multiple devices in parallel (use mult=10 to get 10 parallel devices).