Changing letter color in a table within a .docx file using Python

If anyone has experience working with the python-docx library or any alternative approaches to accomplish this task, I would greatly appreciate your guidance. Specifically, I'd like to know how to change the color of a specific letter within a table while keeping the rest of the text unformatted.

from docx import Document
from docx.shared import RGBColor

def change_text_color(docx_file, text_to_change, color):
    doc = Document(docx_file)
    color_changed = False
    for table in doc.tables:
        for row in table.rows:
            for cell in row.cells:
                for paragraph in cell.paragraphs:
                    for run in paragraph.runs:
                        if text_to_change in run.text:
                            run.text = run.text[:9]
                            run.font.color.rgb = color
                            color_changed = True
                            break
                    if color_changed:
                        break
                if color_changed:
                    break
            if color_changed:
                    break
        if color_changed:
                    break
    modified_docx_file = "modified.docx"
    doc.save(modified_docx_file)
    print(f"Modified DOCX file '{docx_file}' with the new text color. Saved as '{modified_docx_file}'.")

docx_file = "C:\\Users\\RAJAGANESH\\Desktop\\New folder\7506 1st Sample.docx" 
text_to_change = "P.O. No.:" 
color = RGBColor(0, 0, 0)  # Red color

change_text_color(docx_file, text_to_change, color)
#Expectaion is to keep P.0. No.: to change black in color whereas the remaining text in that cell keeps unformatted. 

Made a lot of changes to your code, hopefully you don't mind that. This should do the trick:

from docx import Document
from docx.shared import RGBColor

def get_runs(doc):
    for table in doc.tables:
        for row in table.rows:
            for cell in row.cells:
                for paragraph in cell.paragraphs:
                    for run in paragraph.runs:
                        yield run

def change_text_color(docx_file, text_to_change, color):
    doc = Document(docx_file)
    color_changed = False

    for run in get_runs(doc):
        if text_to_change in run.text:
            pos = run.text.find(text_to_change)
            text_before = run.text[:pos]
            text_after = run.text[pos + len(text_to_change):]

            run.text = text_before
            new_run = run._parent.add_run(text_to_change)

            # Copy the font properties of the original run to the new run
            new_run.font.name = run.font.name
            new_run.font.size = run.font.size
            new_run.font.bold = run.font.bold
            new_run.font.italic = run.font.italic
            new_run.font.underline = run.font.underline

            # Set the new color
            new_run.font.color.rgb = color

            run._parent.add_run(text_after)

            color_changed = True
            break

    if color_changed:
        modified_docx_file = "modified.docx"
        doc.save(modified_docx_file)
        print(f"Modified DOCX file '{docx_file}' with the new text color. Saved as '{modified_docx_file}'.")

docx_file = "C:\\Users\\RAJAGANESH\\Desktop\\New folder\\897506 1st Sample.docx"
text_to_change = "P.O. No.:"
color = RGBColor(0, 0, 0)  # Black colour

change_text_color(docx_file, text_to_change, color)

(I wrote this on my phone and didn't test it yet because I am not home, so let me know if it doesn't work)

Edit:
I am back home. I tested the code and fixed all the issues with it. Still let me know how it goes.