She is easy to spot, very loud, appears entitled, and likes to be observed. She may think she knows everything and that she’s right.
As a know-it-all, she is a person who obnoxiously purports an expansive comprehension of all topics and situations when in reality, her comprehension is extremely limited.
Her display may or may not be directly expressed, depending on the day. A linguist friend understands the German description “Besserwisser’ which is used in other languages, literally meaning better knowing.