Overwrite taxonomy and post type

My theme came with a custom taxonomy post type.

I want to rename the original and duplicate it with another different name.

I tried finding everything relative in functions.php and copy it over to the child theme assuming it would override the parent theme.

Upon refreshing the site it went blank.

Any ideas?

Should I copy the whole functions.php and use that in my child theme. Or is it possible to override?

or maybe it broke the template (even though I was not on a relative page) trying to call that which I changed?

Thank you in advance. I know it’s probably really simple I just don’t know enough about WP yet.