Tell us what you are trying to do?
I'm trying to create a custom field with the field type -> taxonomy to populate this field with the taxonomy terms associated.
In ACF you can simply choose Field type: Taxonomy and after select which taxonomy to display in the custom field.
Is there a similar example that we can see?
Yes the screenshot linked. The custom field is a dropdown linked to the taxonomy by the field type-> taxonomy. If I changed the value in the dropdown and update the post, the taxonomy will changed accordingly to the custom field value.
Note that I don't want to use the checkbox on the side of the screen where the taxonomies are to select it, that's why I want it in a custom field.
This solution actually works, however it is an undocumented hook. There are talks about either adding it to the docs as there are many requests for it.
However this is not something I can say if will happen or not.