Depends on the printer, the large Vorons use high wattage ac heaters and are self enclosed, I have fans on mine that force air under the bed, can easily push into the 60s in the summer. My prusa in its enclosure maybe does mid-high 40s, but I have no issues with warping, did all my original voron prints on it and still use it for smaller/quick prints, good adhesion helps a lot, for small stuff I don’t always preheat for abs. I pretty much run Buildtak surfaces on my printers, it’s replaceable if it’s damaged + adheres extremely well so I can get away with being a bit more carefree.

Haven’t personally needed additional heating other than maybe a space heater in the garage to stop things from kicking out on a low temp when not in use, did consider modding one into the enclosure but I’m personally thinking about going for insulation first.

I’d be cautious about a long term extension cord outside, I’m not an Electrician or an EE so I won’t give you advice on that, be nervous I’d clip it mowing the lawn at the minimum, mains spooks me so I give it an overabundance of caution.