singing in style of robert plant

how can i sing in incredible power like robert plant does? 

Some singers, due to their anatomy (and structure of their resonators), just have naturally louder voices! More important than volume is the quality of your tone. If you hear a lot of air leaking through, then compression exercises should help. Check out day 10 (cord compression) and day 15 (FAQ and troubleshooting). 

I'd also suggest you spend time vocalizing on SOVT's like lip trills, singing through a straw, and using an MM, NN, or NG. All of those configurations help line up your vocal folds properly, which is crucial to avoiding a breathy tone (ie: insufficient cord closure and air "leaking"). 

Training on any of those configurations (SOVT's) or compression helpers (initial G, B, or Y sound) are great; you can also incorporate some exercises that start with "training wheels" and then remove them. For example: sing the same pattern on GOOG, then GOO, then YOO (or something similar). 

Here are some more tips on increasing vocal power:

More power can come from increased compression (AKA vocal effort) and/or increased breath support/air resistance. The two go hand in hand, in my experience! 

Make sure you're adding power with increased bodily engagement, not increased "squeezing" or "pushing" from your throat. The gentle "pushing out" feeling in your low abdomen (of your normal “breath support”) can intensify to a little more of a "lean" or "slight grunt" feeling. The important word is “slight”: we do not want to squeeze or lock up the abdomen! 

The other thing you can play with is brighter, more forward resonance - that's not necessarily power, but it does sound louder and can be perceived as more powerful. 

thanks a lot Camille! one more thing, does Robert Plants use belting a lot or is it just his voice?

Sounds like he's using mixed voice in his upper register! Do you have a specific song in mind?

on black dog maybe.

Black Dog sounds like a lot of mix to me!

ok thank you so much Camille!

Sure thing!