In Spring can you give an example where isolation level is used along with propagation?

I want to perform isolation level along with propagation How I can achieve it. Suppose inside RequiresNew I want to do READ_COMMITTED in DB.

Is Declaring @Transactional(propagation = Propagation.REQUIRED,isolation=Isolation.READ_COMMITTED) valid?

If yes,How it will internally work?

Creating only @Transactional(isolation=Isolation.READ_COMMITTED) will create a new transaction? If yes, will it be a new transaction every time behaving like RequiresNew?