@Keepyourheadscrewedon,
Of course they won’t ‘give up’, but what can a rifle do against a tank?
Russia will take the air, the power stations and the communications arteries.
Then, as I said, war gets confined to house-to-house in cities, which is where Russia will run into trouble if they really want to occupy Ukraine.
They may just leave the cities alone, though, and offer an election with a puppet government on offer, with both carrots (financial aid, trade) and sticks (no power, no free travel).
Then, when puppet government installed, just leave a light military presence to ‘aid the transition ‘.
The hardest thing is to understand what Putin wants. Is it glory? Is it to regenerate the USSR? Or is he genuinely scared of NATO and is this his Bay-Of-Pigs moment? And, of course, the scariest option, that he is genuinely not entirely sane.