This might be a bit hacky, but it works.
As per the docs, you can access the text_frame
of the title placeholder shape.
Thanks to that, you can fetch Paragraph
objects within this frame with the paragraphs
attribute. In the elements section here, you can see that the title
placeholder shape is in the first index (if it exists).
Then we can now get the Font
being used in the paragraph, and change different attributes of it, as follows:
from pptx import Presentation
from pptx.util import Pt
prs = Presentation(ppt_filename)
slide = prs.slides[0]
slide.shapes.title.text = 'New Title'
slide.shapes.title.top = 100
slide.shapes.title.left = 100
slide.shapes.title.height = 200
title_para = slide.shapes.title.text_frame.paragraphs[0]
title_para.font.name = "Comic Sans MS"
title_para.font.size = Pt(72)
title_para.font.underline = True
Extra References: