This article helps you to find the Project Template id that is created using Delegated Project Creator for Jira app.
Option 1:
The below request will result in all the available Project templates.
https://your.jira.url/rest/projecttemplates/1.0/create-templates/all
Refer to this screenshot.
Please refer to this link /all for more details.
Option 2:
You can also get the project template id from the database. Please execute the below query to get the detail.
select * from AO_275653_PROJECT_TEMPLATE;
Refer to the below screenshot.