(verify with datasheet):
Comprehensive Overview of the IRLML6401TRPBF P-Channel MOSFET irlml6401trpbf datasheet
The SOT-23 package has a very high thermal resistance (Junction-to-Ambient $\approx$ 110°C/W). irlml6401trpbf datasheet
An N-Channel MOSFET is usually placed on the "low side" (between load and ground). If placed on the high side, it requires a voltage higher than the supply rail to turn on (Bootstrapping). irlml6401trpbf datasheet