I wonder when parsed process definition is actually instantiate

Hello Camunda Team,
I made a web application using spring frameworks based on documents provided by camunda(Camunda Platform 7 documentation | docs.camunda.org).
As far as I know, Deployed BPMN files are parsed by BPMN Parser and stored in camunda database (example, H2 database).
I wonder when parsed process definition is actually instantiate, as an Java object running in the process engine.
Is it stored in database? Or is it to read the entities stored in the database when starting the process using the startProcessInstance API and make it object?

When stored in camunda database, object variable was thought to be found in camunda database schema Process Definitions table(ACT_RE_PROCDEF) if stored in a serialized array in CLOB, but it was not found.

If I have the wrong knowledge, please give me feedback.