Nilton, great question and often one of the most overlooked aspects of diligence. In early stages, going to the physical office can shed a lot of light on what life at the company looks like. You can also ask questions about go-to-work, how work is done, etc and ask about staff benefits. I’ve actually created a methodology to assess culture in this regard given how limited outside tools/assessments are.
In diligence a deep dive operating meeting about how work is conducted, along with HR review of staff turnover rates, etc. can yield insight into how happy staff are.