Relegation isn't enough. They will just bounce right back up if that's the only punishment. They need to have a multi-year transfer ban and a massive fine levied against them as well.

And all their trophies (or at least the domestic ones, where the FA has authority) should be taken from them. Even if they don't hand them to the 2nd place team, just null them out for that season. And that should include every season between 2009 and 2026, not just the years that they were explicitly charged with. It's not like their finances were magically rectified in 2019. Every season after 2018 is tainted too, because those further sessions were built on the cheating from the 2009-2018 seasons.