Dynamic Content API - Field with prepared and custom value input

I would like to create my own dynamic field that works like the post meta field, for example. Either you select a suggested option from the select field or you can enter your own key.

screenshot_ 2025-11-05 um 15.52.21

Unfortunately, I couldn’t find out from the documentation or the source code of cs whether this functionality was programmed specifically for this purpose or whether there is also an option for it.

Thanks in advance