Yes, but a competent PM could slow the spread of the poison just enough to make the Tories' path back to power easier. There is a difference between 250 seats at a general and 300.
At the moment a recovery in the polls would get them nowhere near 250. Maybe 150. There is an odd cognitive dissonance at the moment where people are at once recognising the hole the Tories are in, but not at all realising the reality of what that would mean electorally under FPTP in a pretty unpartisan polity.
If there was an election tomorrow the Conservatives could quite credibly end up with 0 seats. Certainly there is a well above 50% chance they would come out behind both the Lib Dems and the SNP.
So basically Liz Truss killed the Queen, the UK Economy, and her party.