If you want to smooth out your lines, then MediBang Pro’s stabilizer is the assistant you need.
Stabilization
Stabilization is an assistant setting for brushes in MediBang Pro that automatically smoothes out any shakes or wobbles in your brushwork as you draw.
The higher the stabilizer is set to, the smoother the line. The lower the stabilizer, the more natural your line-art feels and looks.
How to Use
Under the options menu, open environmental settings and select your preferred level of stabilization.