Advanced Group Policy Management logoDespite several Microsoft Advanced Group Policy Management pages saying

You can centrally configure optional logging and tracing for Advanced Group Policy Management (AGPM) using Administrative templates.

they don’t tell you where to find the Group Policy AGPM.ADM or AGPM.ADMX files.

After much searching, and time wasted; I can tell you that if you install the AGPM client, you will have a copy of AGPM.ADMX dropped into your local %windir%\PolicyDefinitions directory.

References:
Configure Logging and Tracing
Ask the Directory Services Team – AGPM Production GPOs (under the hood)
Active Directory Infrastructure Self-Study Training Kit: Stanek & Associates Training Solutions