small_caps_script.py

import bpy

''' more options per character 
character.use_bold 
character.material_index
character.use_italic
character.use_underline
'''
def set_body(text_object, normal, small_cap, small_caps_scale=0.39):

    data = text_object.data
    data.small_caps_scale = small_caps_scale
    data.body = normal + small_cap

    for idx, character in enumerate(data.body_format):
        character.use_small_caps = (idx >= len(normal))


text_object = bpy.data.objects['Text']
normal = 'Maintext '  # add space here, or at the start of the small_cap
small_cap = 'smaller'

set_body(text_object, normal, small_cap)