Hello @luke314pi

how can I increase the size of the logo, and increase the height of the header to accompany it?

To increase the size of the logo upload the logo of you required size and you can further you can adjust the size with some custom CSS.
For this you need to go to Admin Panel / Appearance / Customize / Theme Options / Advanced Options.
Here you need to copy and paste below CSS:

.custom-logo-link img {
    max-height: 170px;
}

Note: You can adjust value 170px according to your need.
Or else for more specific answer you need to post your site URL.
Let us know if the problem is solved.

Regards!!!

Hello @luke314pi

Sorry for the inconvenience.
Please try adding below custom CSS. You can remove the above given CSS.

.custom-logo-link img {
    height: 155px;
}

Hope this works.
Let us know how it goes.

Best Regards!!!

Hello @luke314pi

Ok for width and height try adding below custom CSS. Remove the above given CSS.

.custom-logo-link img {
    height: 155px;
    max-width: 500px;
}

Hope this works.
Let us know how it goes.

Regards!!!