Are there any components other than receiver, speakers, amp, and bass that I need to complete my system?

I am getting a new car stereo, and I need to know what all components to get.

I know I need a receiver, but is it recommended that I also purchase a sound processor or some other component I haven’t heard of?

I know I need some speakers, but is there any other components that go along with speakers? (Like these speaker boxes, what are they?)

I know I need a sub, but what kind of amp do I get?

To some it all up, Are there any components other than receiver, speakers, amp, and bass that I need to complete my system?

Thank you for the help!