Apply Custom Word Headings

I have the full text ready in a single Microsoft Word document, but the hierarchy of headings is still missing. What I need is for you to take that content and assign proper Heading styles so the document is organised into main headings, sub-headings, and normal font—three levels in total—exactly following the custom style set our team has already defined.

You will receive:
• the Word file with all text produced with font and colour all done.
See attached what it looks like

Your task is simply to apply those styles consistently throughout the file so the navigation pane and any future table of contents work perfectly. Once done, return the updated .docx; no additional graphics or layout tweaks are required.