You'll get a lot of cynical takes on the internet because a lot of people have had bad experiences with consultants. Or more accurately, bad experiences with management who hire consultants for some goal.
The underlying goal in a lot of consultant engagements like you describe is to get something done outside of the inertia of your org structure. As companies grow, people get set in their roles and become resistant to change. Trying to make change things, start new initiatives, or shake things up will often fail if it doesn't fall neatly into the inertia of the company.
Hiring a consultant is like inserting someone out-of-band who can generate some outside analysis without feeling obligated to respect all of the hidden politics, histories, and strong personalities that can come to shape a company.
Now whether or not that goal is inline with your own goals at this company is a different question. It could be that the outcome involves a new initiative that makes your work better by removing some of the painful organizational cruft that has built up over the years. Or it could become an effort to reshape the parts of the organization that you personally liked. Or maybe the consultant is taking notes for some entirely unrelated initiative that you'll never see.
You don't know, but I would suggest making a good faith effort to work with this person while they're in your company.