If someone had a large portfolio on Coinbase and wanted to sell it, do they just press the sell button?

I have read that if you sell by pressing the "sell" button that the actual price that you get may be lower than what you think the current price is. Also, assuming someone converted to USDT and the to USD, are there any extra steps along the way? I've heard of coinbase freezing an account and the person not being able to sell, are there ways to avoid that?

Also, what strategies are there to avoid as many fees as possible? I've read something about Coinbase pro? What abount the receiving bank, do they have any qualms with receiving a large sum from Coinbase?