In episode 5 of the last season of the Attack on Titan anime, Willy Tybur claims Eren Yaeger could use the colossus Titans in the world to attack, because he isnt tied by the oath of peace as those who have royal blood are. But in the other hand, supposedly for not having royal blood Eren can't control other Titans with the Founding Titan ability. Then, why Willy Tybur claimed Eren could attack using the colossus Titans in the walls, if supposedly Eren can't control that ability?
There are two reasons. First one is because he inherited the founding titan from Grisha. As long as he has that power, the possibility of him using that power exists.
The second reason is the information they got from Reiner and Bertholht. To their (Reiner and Bertholht) eyes, Eren was using the co-ordinates without having royal blood. The reason he could do this was because he came in contact with Dina Fritz who had turned into a pure titan, but since they didn't know that, they reported back to Marley that Eren used founding titan while not having royal blood. This led them to believing that Eren could use the powers of founding titan.