Straw man
A straw man is when you make the other person's view sound sillier or more extreme than it is, so it's easy to knock down. You argue against a distorted version of their position instead of their actual position. That's unfair and doesn't settle the real disagreement. The fallacy is to misrepresent then refute—to beat a dummy instead of engaging with what they actually said. The remedy is to represent their view accurately and then respond.
Examples
They want to use less petrol. So they want to ban all cars and wreck the economy.
She said we should review the policy. So she wants to tear up everything we've done.
He suggested we trim the budget. So he's in favour of slashing essential services.