Let's see the chapter to see to whom luffy called powerful.
It's quite weird if Luffy is referring to Kizaru ( yes he is powerful) but it still doesn't make sense
Oda didn't make Luffy and zoro say something like this when Shanks and GB were in wano
Then, present chapter progression is like this
1)Luffy talks to Saturn and kizaru arrives at Egghead and engage with senta
2)then we have york and SHs
It's at the last page of the chapter, Luffy says "someone powerful has come"