Looking at pandas.read_sql official documentation it says:

ADBC provides high performance I/O with native type support, where available. Using SQLAlchemy makes it possible to use any DB supported by that library. If a DBAPI2 object, only sqlite3 is supported. The user is responsible for engine disposal and connection closure for the ADBC connection and SQLAlchemy connectable; str connections are closed automatically. See here.

Since you are using SQLAlchemy it handles the closure automatically.