Hi Patrick!
Thanks for reaching Microsoft Community. We're here to help and let's work on this together.
With your query, yes, you can still use headphones or wired earbuds with the Surface Pro 9 by using a USB-C to 3.5mm headphone jack adapter. This adapter can be purchased separately from Microsoft or from third-party retailers. To listen to music using headphones or earbuds, simply plug the adapter into the USB-C port on the Surface Pro 9 and then plug your headphones or earbuds into the adapter.
Thanks again for choosing Microsoft. Hope this helps!
Regards,
RodelioP.