How can Putin save face?

Former MI6 Chief, Sir Robert John Sawers, says

we need to be a little bit careful about how we do that, we must leave Putin a way out

And Yuval Noah Harari says:

Nobody could say for sure how the Ukrainian people would react. There was always the option that Putin's fantasy would come true. Maybe the Russians would march in, Zelenskyy would flee, the Ukrainian army would just capitulate, and the population would not do much. And now we know this was just fantasy. Now we know the Ukrainians will fight.

And this derails the whole rationale of Putin's war. Because you can conquer the country maybe, but you won't be able to absorb Ukraine into Russia.

The only thing Putin is accomplishing is planting seeds of hatred in the hearts of every Ukrainian. Every day this war continues is more seeds of hatred; it will last for generations. Ukrainians and Russians didn't hate eachother before Putin - they were siblings - now he is making them enemies and if he continues, this will be his legacy.

Interestingly, the interviewer actually puts the question to Harari, asking:

Putin needs to win - how do we square these things?

And Harari's response:

...I don't know!

Question:

How can a leader of a powerful country who underestimates a weaker opponent and needs to withdraw, do so without losing face domestically and internationally?