I went from working at a Fortune 500 with > 100k employees to a small firm with less than 500 people. You would get weird looks from people in the Fortune 500

I went from working at a Fortune 500 with > 100k employees to a small firm with less than 500 people. You would get weird looks from people in the Fortune 500 if you wore jeans into the HQ. You might bump into the CEO (literally did that once) and you don't want to stand out. At the new place, I just wear what I want. Usually jeans, polo or nice t-shirt and some kind of fleece/sweater like thing if it is colder out. Some people wear shorts and flip flops in summer. I think it is a culture shift - some places like Fortune 500 tend to focus more on form rather than function. Lots of ceremony and bureaucratic work practices like getting approvals for things and checking with management for every little action. You would get slightly mocked if you dressed above your pay grade. Smaller companies, and maybe the culture where you are, want less formality and are more casual. Your actions at such a place speak louder than your clothing choice. I like just dressing "as myself" basically how I would dress on any normal Saturday. If a company makes me feel like I need to change from that, I treat it like a uniform. For meetings - are they with customers? If so, ask someone that maintains the relationship with that customer what is appropriate. For interviews - check the company out, see what social media shows people wearing if it isn't stock photos. And dress a bit above what you think everyone wears to work.