Lead magnet
Why it matters for creators
The lead magnet is the reason anyone comments your keyword, which makes it the part of a DM funnel most worth getting right. Everything downstream is machinery; this is the offer.
Two properties separate the ones that work. It has to be instantly useful — something the person can open and get value from in under a minute, because the whole appeal of the DM route is immediacy. And it has to be specific to the post it sits under. A general "free guide" attached to every post converts far worse than a narrow thing that answers the exact question the post raised, even though the narrow thing is smaller.
On Instagram the delivery is a link, so the magnet needs to live somewhere linkable. The friction people underestimate is the landing page: a link that opens to a form asking for a name, email and phone number will lose most of the audience that a well-written keyword just earned you.