I’ve been trying for a week to find a way to repeat this animation. Please tell the technique, what parameters the objects should have. Very important

To expand vellum objects mid-simulation, you need to increase the f@restlength primitive attribute on your constraints. You can do this using a Vellum Constraint Property SOP, or if you need more precise control, use a Geometry Wrangle or a SOP Solver set to operate on the ConstraintGeometry data (rather than the default Geometry). If you're using a Geometry Wrangle, make sure it's set to run over primitives. I'm attaching an example of that here.

Then you just need to collide those expanding objects against some other Vellum object or patch in the simulation.