Civil/environmental: What can I expect on the my second interview that’s only 30 minutes long?

I am a Civil/Environmental engineer and work in waste and landfill gas management so there aren’t many competing companies for me to switch between. This also means there are few people with the required skills to support growing work in this field. I had a first interview round with the VP and the engineering director of the company division. The discussion lasted about 50 minutes and it ended on a high note. I received emails about possibly receiving an offer and that they’re interested in me as a candidate. I have another call scheduled tomorrow for 30 minutes with a project manager, and 2 others who I couldn’t find on LinkedIn. Would this be more of a culture fit call? What can I expect?