ᐅ How do I unscrew this fixture?

Hello everyone,
I recently bought a new faucet and would like to install it in place of the old one. I started removing the old faucet and was faced with the following situation (pictures). I’m quite unsure and don’t know how to proceed. Does anyone have any idea how to unscrew this and which tools I might need?

Best regards,
Louis

You need to loosen that first. Then everything will come off.

1. Remove the rod of the stopper mechanism.
2. Unscrew the inner cone using a large flathead screwdriver.
3. Unscrew the large cone using a large flathead screwdriver. Alternatively, a water pump plier? It could also be a hexagonal shape, which is not visible in the picture. Probably a 10mm (3/8 inch) socket wrench?

Thank you for the responses! They were very helpful. The new faucet has been installed!