How you feel right now it's completely normal and expected because you are young and you want to learn and gain knowledge. I have changed 4 companies because I was searching for the job where everyone is writing clean code and where best practices, code review, and learning are on the high level. You can forget about that because managers don't care how your code looks like, or if you are using best practices to achieve your goal. Now what I'm doing, I'm trying to get as much as possible time on estimates, that's how you can have time to write clean code, and to learn something. If you are estimating the task, add also the time you need to review what you did and do not be scared of refactoring, if you see that something is written in a wrong way, rewrite it, don't blame around :).

Also, work and learn at home. That's your time and you can learn and do whatever you want.

Keep in mind that there is no job where everything is perfect, so collect all negative things you have at the current position and try to change them. If that's not working then leave :)

What managers love is the example and real POC. So if you think that something is wrong or old, create a POC, make a demo. That way you can get some time and resources to do something new and interesting. Don't think someone will give you such project just like that :)