You get to chose the % match in the creation process.
https://experienceleague.adobe.com/docs/experience-platform/segmentation/ui/lookalike-audiences.html...
Create a Look-alike audience
IMPORTANT
You cannot use a Look-alike audience as the base audience for another Look-alike audience. That is to say, you cannot create chained Look-alike audiences.
To create a Look-alike audience, you’ll need to select the audience you want to base the Look-alike audience off of. To access your list of available audiences, select Audiences in the left navigation bar, followed by Browse. The list of audiences appears. On this page, you can select the audience you want to use as your base audience.
On the audience details page, select Create look-alike audience to begin the process of creating a Look-alike audience.
The Create a look-alike audience popover appears. On this page, you can set the similarity percentage for the Look-alike audience.
You can set this similarity percentage in three different ways:
- Move the slider to set the similarity percentage
- Enter the similarity percentage in the numeric entry box next to the slider
- Hover over the graph and select the desired location to set the similarity percentage
You can also update details about the Look-alike audience, including its name and description. By default, the Look-alike audience’s name will be generated based on the base audience’s name and the similarity percentage previously specified.
