Fans gently blowing on your plants naturally causes them to become stronger. In nature, the plants build up stem strength when it gets breezy for self preservation.
I use silica blast in my feeding solution from day one and it makes for very strong branches and stem.
if you want really strong stems, I highly suggest LST over any branded nute solution... albeit i'm not claiming to know everything, but i'm talking specifically from my own experience. my first grow, stems were flimsy AF and everything was practically falling over under it's own weight, and those weren't even very heavy colas. this time around, I gave my lady some heavy LST and 2-3 weeks extra veg time and the difference stem girth is insane. that's not to say other techniques won't work, but this is definitely a sure-fire way to grow bigger/better stems. i'm skeptical to believe that a single nute solution could reproduce the same results.
My DWC plants almost never need any support of branches at all compared to my other hydro methods. I've grown the same strain in promix/perlite and DWC. The DWC version has stems that are at least twice the size. I feed them the same feed. Silica supplements are known to help build strong stems. Good air circulation blowing gently on the plant rustling it about also will build structural strength.