Jay D. answered 04/26/19
Undergraduate Honors Student Majoring in French Secondary Ed.
In formal essays, you can use italics to add emphasis to a word, as would be the case here, though italics are most commonly used for book titles and foreign words. So, you technically can use italics in this case without being grammatically incorrect, but I honestly would advise against it. I don't think your sentence with "every" in italics is meaningfully different enough from the same sentence without italics to warrant the use of such ornamentation. Instead, you could emphasize your point by providing examples.