Set Base Color for multiple materials of multiple objects name starts with 2nd arg.

set_base_color.py

# https://blender.stackexchange.com/a/158902
def srgb_to_linearrgb(c):
    if   c < 0:       return 0
    elif c < 0.04045: return c/12.92
    else:             return ((c+0.055)/1.055)**2.4

# https://blender.stackexchange.com/a/158902
def hex_to_rgb(h,alpha=1):
    r = (h & 0xff0000) >> 16
    g = (h & 0x00ff00) >> 8
    b = (h & 0x0000ff)
    return tuple([srgb_to_linearrgb(c/0xff) for c in (r,g,b)] + [alpha])

# example: set_base_color(0xff00ff, "Sphere")
def set_base_color(hex, name_start_with):
    for obj in bpy.data.objects:
        if (obj.name.startswith(name_start_with)):
            obj.active_material.node_tree.nodes["Principled BSDF"].inputs["Base Color"].default_value = hex_to_rgb(hex)