If you are talking about the stock widget, I couldn't get that one to stretch all the way across the screen. On either phone. Take a look in the widgets. There is another version that spans 5 x 1. I think it should work if you using 5 x 5 grid or smaller.
Interesting. The larger one you can shrink by 1 box on the 5x5. However it puts the time on the top right and weather on bottom left with gaps in the other corners. I wasn't definitely able to resize the small widget on the Note 7. I did notice that the small widget on the Note 7 included high/low. On the Edge it does not. The weather portion of the large widget on the Edge is what my small widget looked like on the Note 7 (i.e. the time portion was not there).