Two options:
these are just examples
"There's a book coming out, known as Harry Potter, that is about a boy wizard and evil forces."
"There's a book coming out known as Harry Potter that is about a boy wizard and evil forces."
Elaborate please
Ignoring the other aspects of your sentences, the choice is one of style. Both are correct. If you read them aloud, they would sound different, and not only for the pauses the commas lend, but also because the commas make the phrase "known as Harry Potter" parenthetical.
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Ignoring the other aspects of your sentences, the choice is one of style. Both are correct. If you read them aloud, they would sound different, and not only for the pauses the commas lend, but also because the commas make the phrase "known as Harry Potter" parenthetical.