Have you ever been an employee (or employer) at a conglomerate? If so, what was it like?

I have worked for Kmart and Home Depot.  It was a job like any other. 

Still am. Origin Energy, a major electricity and gas company in Australia. I get my share of Karens to deal with.

I worked for a global, multinational, conglomerate, corporation for over 35  years. Frequent mergers, acquisitions, and divestitures meant constant change and uncertainty. The management, culture, and headquarters changed over the years, although, for my company, the name remained the same. So, the company my grandmother worked for was quite different from the one I retired from, despite having the same name. Many times, the changes meant that financial reports had to be restated which affected my own workload. Another feature of working for a conglomerate is that you can take a job in a different industry without changing employers. 

I've worked most of my career in law firms.  I started out in a medium sized one, went to a three-man shop, then worked for a larger one.  Over the years, firms merge and if I didn't care for the new culture, I moved on.  The last move was when the medium sized firm merged with a large firm and, between the two, I worked with the same boss for 32 years.  He and I retired this past January.