The new dollar coin is exactly the same size as the previous Sacajawea version.
It's also the same size as the Susan B. Anthony dollar too. But at least the portrait was different. I don't think there's enough difference between the size of a quarter and a dollar coin to easily differentiate them. There's a reason US citizens keep rejecting dollar coins of that size, even though inflation keeps decreasing the value of coins. Even if it took 4 quarters to buy what one quarter used to, most people would rather use 4 quarters rather than on dollar coin.
The Sacajawea coin was pretty close to the size of the Susan B. Anthony.
Which, itself, was pretty close to the size of a quarter.
I see a pattern here....