Most top Tech companies do at least some code review especially on every change.
Some companies have rules about how many people have to review each piece of code. I’ve never felt that to be necessary; I prefer a simpler system where the only rule is that each piece of code must be reviewed by one person. In practice you’ll still send reviews to the people responsible for maintaining the particular code you changed, but it’s nice to not have the hard requirement.
If you do it right, code review shouldn’t feel much difficult. You and your reviewer aren’t adversaries; you’re working together to build the best software you can together. (It’s important to not take feedback personally – even if your code needs to be changed, that doesn’t mean you are problematic. It’s normal to get feedback, and that’s what helps you grow!)