How to trigger a new endpoint installation?

First my setup and migration plan.

i have two servers. An old one 2008R2 and a new 2019 to which i want to migrate. Both servers running fine, have same identity and so on.

The RMS is still configured to point to the new server on the old one 2008R2. I only need to start a new "setup call" , so the clients move automatically to the new server.

I don't want to use a domain-admin account to reinstall manually from the console.

The automatic setup for "clean" clients is done by an client computer startup script set via GPO. Works perfect.

I'am waiting for 2 months now, for a new Sophos client release newer than 10.8.11. This would result in a smooth automatic migration. But this does not happen! So i need an other method to trigger a (onetime) Client setup. This should run automatically.

Any suggestions are welcome

Thanks!