Blender import PLY file with all attributes

import bpy
# clear all visible
bpy.ops.object.select_all(action='SELECT')
bpy.ops.object.delete(use_global=False)

# PLY file name
name = "robot"

#impoprt PLY
bpy.ops.wm.ply_import(
    filepath="path-to-file/%s.ply" % name,
    import_colors="LINEAR",
    import_attributes=True
)
# doc:
# https://docs.blender.org/api/current/bpy.ops.wm.html

# create the color attribute on the object's geometry
bpy.ops.geometry.color_attribute_add(name="Color")

# store ref to mesh
mesh = bpy.data.objects[name]

#create geometry node
geom_node = mesh.modifiers.new('geom_node',type='NODES')

#Create a pointer to the node tree
tree = bpy.data.node_groups[0]

#Set that tree to your modifier
mesh.modifiers['geom_node'].node_group = tree

#set the "Color" attribute as the output of the Geometry node
geom_node["Socket_2_attribute_name"] = "Color"