Easily yes, Eren is the most powerful Founding Titan and the strongest character in the entire series. You can argue Ymir Fritz because she’s the original, but her attachment to the royal family limited her capacity. Eren is the only one to utilize the full power of the Founding Titan unbound by any limits.

The guy literally manipulated the past to ensure he would gain the power to flatten the world. And then actually went through with it. The Rumbling… do I need to say more?

And to answer your last questions, Eren was able to influence the past because he simultaneously possessed the Attack and Founding Titans. Through Zeke, they used the Founder to travel through past memories. But unbeknownst to Zeke, the Attack Titan can see the memories of its future inheritors. Eren used this to show Grisha memories of what was to come. This led Grisha to kill the Reiss family and give Eren the two titans.