No, we have never seen the full extent of Shanks' power nor the Red Haired Pirates in general has we haven't gotten a actual fight from them yet. As you saw, it was pretty much foreshadowed that the Red Haired Pirates vs the Blackbeard Pirates is going to happen sometime down the line. It was pretty much confirmed in chapter 957 by Brandnew that Shanks' Commanders have the highest bounties out of any Yonko crew and they have all made a name for themselves and are feared and respected by all the pirates in the New World. Plus it was said that the Red Haired Pirates are the most balanced crew meaning in a scenario where all the Yonko crews would have a war with each other, the Red Haired Pirates would most likely win. Don't read chapter 957 because it has MASSIVE SPOILERS like the bounties of all the Yonko including the bounty of the late Gol D. Roger.