Godot's ParticleEmitter2D is a bit limited in terms of controlling individual control of particles, which means, that setting the random parameters and ramps is about as far as it gets for that, which is enough for a lot of cases though! But in return for that, the engine's ease of use is undefeated.
However, if you're fine with that, you can easily access all the parameters of the ParticlesMaterial.
var mat = $Particles2D.get_process_material()
mat.angle = 45 / idk right now if it's in radians or degrees
mat.angular_velocity = 3
# setter version