Hello, you can enter the company name in the patent database (there are many free ones online). If they apply with the company as the applicant and entrust a patent agency to apply, then you can see the name of the patent agency in the search results.
For example, look at Baidu. The screenshot is as follows:
Click to view the description of any patent application, and you can see the name of patent agency (74):
I hope I can help you!