If by we you mean some humans then maybe. If by we you mean you or I, unless you’re Charlie Koch levels of rich, almost certainly not.
Mars is a fraction of the size of Earth and has less than half the sunlight for solar panels or growing plants so even if we did make it habitable and had unlimited resources for shipping people to it (which, even purely theoretically with maximum efficiency, is quite expensive), it would probably be impossible to sustain more than a small fraction of Earth.
Generation ships could be arbitrarily large but the materials cost is and probably always will be absurdly expensive, especially accounting that it has to survive for hundreds of years, even small things like migrations of electrons in computer chips add up to cause longterm damage over that long of a timeframe. Plus it has to be able to survive a meteor impact and/or internal sabotage. And with all that in mind imagine being able to save even 0.01% of the world (750,000 people)