odoo16/addons/mass_mailing/data/ir_config_parameter_data.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <data noupdate="1">
        <!-- Enable Mass Mailing Reports -->
        <function model="ir.config_parameter"
                  name="set_param"
                  eval="('mass_mailing.mass_mailing_reports', 'True')"/>
    </data>
</odoo>