No, not magnets. The magnetize pose is in the Pose library, in the Pose->DAZ's Victoria 4->Magnatize Clothing folder. It's a pose that helps clothing fit.

Here is an example. This is 2 lots of Aiko4 with the basicwear bikini on. The one on the left is what happens when Aiko4 is posed. The one on the right was posed the same, but this time I applied the magnetize pose to the bikini, which fixes it. That is what the magnetize poses are for.