Unlikely. First, CO2 is actually poisonous to humans unless it is less than 1% of the atmosphere. So no way you could survive in a CO2 atmosphere with just an oxygen mask. They would need a closed system like divers use supplying air with both oxygen and nitrogen. The open system used by Everest climbers or jet fighter pilots wouldn't work, they would die of CO2 poisoning.

As for the amount of CO2 on Mars, so far we know of enough to about double its atmospheric pressure to 2%. That's not nearly enough. What's more, there is an equilibrium at 1% with Mars at its current inclination and orbit. So if you increase it to 2% it will soon fall back to 1% again as 2% is an out of equilibrium state - unless you keep it out of equilibrium for instance with giant orbital mirrors or greenhouse gases.

There's a runaway reaction at 10% but there might not be enough CO2 present to raise it to 10%. Indeed if there is that much CO2 there, why has it not gone into that runaway greenhouse effect naturally in the past at times when its atmosphere gets thicker?

Used to be thought there might be plenty of CO2, but now the pendulum seems to be swinging in the other direction, probably there isn't that much CO2 left on Mars.

Chris Mckay has suggested we should transform Mars into a Mars like climate instead like the one it had in early Mars, especially if we find Mars life there.

But even then - if we can't get it above that 10% level, there is probably not enough CO2 there to do that either. Except by having greenhouse gas factories running continuously, which would be enormously challenging and expensive.

Chris McKay describing his idea briefly back in 2004. Lots of more extensive treatments of it if you search. Giving Mars Back its Heartbeat - Astrobiology Magazine

My vote would be for leaving Mars as it is. We are a young species and have millions of years in the future to transform Mars when we may be wiser and at least know more about exoplanets. So have plenty of time to do it. And if we can't survive that long, we have no business taking on the responsibility of starting life on a new world seems to me. As we'd need to be around for at least thousands of years and probably millions of years to see it through to the stage where it is stable and has a decent long term future, during which time a lot could go wrong.

To set a planet on its way towards terraforming and abandoning it after a few decades or a century or two, to my mind is like setting a baby adrift on an ocean - you know it will be fine for the first few meters but once it gets out of sight you have no idea, depends on some stranger finding it and rescuing it.

I think it is useful to think about ideas for terraforming. Doing that can help us understand the Earth and exoplanets. But after all it's a case of trying to speed up  a process that took billions of years on Earth. Maybe it can be sped up to just a few thousand years, but I think we need to know a huge amount more than we do at present before we can say that with any confidence at all.

See also my Trouble with Terraforming Mars

Why Nukes Can't Terraform Mars - Pack Less Punch Than A Comet Collision

Our Ethical Responsibilities To Baby Terraformed Worlds - Like Parents