Everything in the User Manual implies there is no built-in antenna but it never says there isn't. But there isn't any reason to think there is one. Look at pages 42 & 43 in the online manual for this model. A couple questions are on "How do I watch antenna TV", and "I see “noise” or static on the screen".
https://cdn.vizio.com/user-manual/PDF/2019/TV/UM/V436-G1_V555-G1-ENG.pdf