Short answer: Thesis-to-article work is usually priced by scope rather than thesis length alone. The editor must know which study or chapter will become the article, the target journal or article type, the amount of restructuring required, and whether language editing is also needed.
A journal article is not simply a shortened thesis chapter. It normally needs a focused research question, concise literature context, journal-length methods and results, and a discussion written for the target readership.
Send the thesis, identify the intended paper or chapter, provide the target journal if known, and state whether you need structural guidance, language editing, formatting, or all three.
The author must approve the final scientific content and ensure the article complies with institutional and journal policies on thesis-derived publication.