Increase dimension of HEADER

Goodmorning,

I apologize for the trouble, but I didn’t find a solution on this website.
I modified the image Header of this site (https://www.casapiazzarreda.it/ ).
The problem: I upload the original image in a format (1300x300 px), meanwhile when i change the image the dimension of Header are too little.

The theme is Metriulium Child (i think that is customized, but I’m not sure).
Please, could you help me ?

Thank you in advance,
Jacopo

Hi forbrukslanNO
thank you in advance for your answer.

The problem is that the size of the header are too small (i talk about the
logo “Casapiazza - Veneta Cucine”).
I would like to increase the dimension of it.
With all the device that i try (pc- smartphone-tablet), the dimension of
logo are too small.

Thank you again,
Jacopo