Is a company bonus entered as a w2?

That depends on how the employer reported the bonus.  What document did they report it on?

The company should have included the bonus on the W2, yes.

Why are you asking? Was it done wrong and you need advice on how to handle?  Although it shoulda been on your W-2, we see frequent cases where a 1099-Misc is used. You can report it that way, but there are a coupe of alternatives

Yes; that is the usual and proper way to report it. It is simply added to your regular salary in box 1 of the W-2.