Read only pdf form after submitting

After confirming the form by clicking the submitbutton, the pdf should no longer be editable (all checkboxes,text fields,...) when opened. Upon confirmation, it will be forwarded to an email address.
The receiver should no longer be able to edit the PDF. 

I have already read some answers to a similar question but they date from previous versions, that a script action could be added to a button / field. It should work with Indesign 2021. Is this also through scripts? How do I create this correctly or can I link an existing script to the button. Unfortunately I see that in the actions for the button there is no longer a possibility to add a script to the new Indesign version.