Yes, if the office preference is relevant and you can explain it credibly, a brief office-specific reason can strengthen the letter.

Useful reasons include geographic ties, partner or family location, language, industry fit or a genuine connection to the office. Avoid generic claims that could apply to any city.

Do not use the cover letter to repeat every office preference you already selected in the application. The point is to add context when the location is part of your fit story.

If the application does not require a cover letter, do not create a weak one solely to explain office preference. A concise, specific rationale is better than a long paragraph about the city.

I mentioned my office because I had family ties there, and it made the preference feel much more credible.