Open the Followers / Reach filter (Creator Filter section) and select the metric Followers — on YouTube it is called Subscribers. Then set a minimum and/or maximum with the range slider. Only creators whose current follower count lies inside the range are shown; profiles below a few thousand followers are generally not part of the influData index at all.
The same filter popover also holds the reach-based metrics (average views per post, plays per reel, shorts views etc.), so you can combine size and reach criteria in one place. Typical use cases: exclude very large accounts with a maximum, or find micro creators with a range such as 10k–100k.