Advantage Lookalike

Formerly known as Lookalike Expansion. When turned on, Meta can expand your audience if it believes you can get better results by doing so. That expansion will be achieved by increasing the percentage of your lookalike audience, using the original custom audience for training. On by default and cannot be turned off when optimizing for conversions or app events. Otherwise, advertisers have the option of turning this on when a lookalike audience is provided for targeting.