Change header size

You can read more about how to do this here:
https://www.ads-software.com/support/topic/make-header-larger?replies=3

Thanks very much. One question, do I create a new function.php and also change the custom-header.php? Do i add that filter to the custom-header.php or overwrite the existing code in it?

Thanks again

You create a new functions.php for your child theme (not the parent theme! That might cause problems); you don’t need to touch or do anything in custom-header.php.

Thanks! Can I just check wherabouts I should add this in the functions file, should it be at the very end of the file?

No worries I added it to line 283 and its worked now! Thanks very much! ??