Genetics play a big role. They also need good light, and no slack on the feeding. Boosters aren’t really needed unless the plant demands more in flower. Buds grown under top notch led, and good spectrum indoors produce some pretty dense nugs. Drying & curing correctly will also help tighten them up.
This was brown outside, but I can imagine the nugs you see going down the branch will probably be of the same density. I’ve grown her inside, and the nugs just sound like they put dents in the tray when dropped on it. I’m currently drying this girl now & the buds look huge on the plant, (tops are like grenades) but when they dry & tighten up they are significantly smaller, (golf balls) however they are dense as ever. The genetics are from thug pug tho. His packs can go anywhere from 60-2k for his packs. Demand is a hellova drug lol
I would just pick up some good reputable genetics, and start there. 
