Some garments are named after what they are. Others after what you miss while you make them.
Sunshine has two techniques that do the exact opposite job. The half brioche makes the fabric dense and heavy, so the garment hangs well. The eyelet pattern opens it up again.
It sounds like they ought to cancel each other out. They don't — they each do their own part of the sweater. Weight where you need drape, air where you need breath.
That is the whole pattern in one sentence, really, and it is why it is marked Beginner plus even though it looks more complicated than that. You do one thing at a time.
Needle 7. It goes quickly, and it is one of the ones I have used the most myself.
Beginner plus · needle 7 · half brioche and eyelet pattern