About custom fields and logic of self-developed forms

Hello, everyone. I have encountered a problem at present. Regarding the custom form in the production order: the production picking list, the user hopes to add a picking list number to the form, and this list number will be printed according to the previous one. The serial number is generated. As far as I know, this tracking number logic cannot be implemented, so I would like to ask you, is there any other solution? Attach a screenshot and brief description,Thank you!