When it comes to finding antonyms for the phrase "looked up on," several options come to mind. To start, instead of looking up on, one could look down on, overlook, or ignore altogether. Conversely, instead of looking up on, one could look up to, respect, or admire. Depending on the context and tone in which the phrase is used, there may be other antonyms that apply, such as belittle versus praise or denigrate versus compliment. Ultimately, when seeking antonyms for a particular phrase or word, it is beneficial to consider the opposite meaning and intention behind the language being used.