Whilst there have been cases of Covid transmission on aircraft, it does not seem to be that common despite being a confined space. The air flow on an aircraft tends to be top to bottom, that is it is released into the cabin from the ceiling and exits through the floor, so that helps reduce particle spread. Recycled air is also filtered, along with clean air from outside, to remove particles including viruses and bacteria. That everyone faces forwards, rather than face-to-face, also helps reduce the risk.
How isolated are you at the moment, as you going into supermarkets, other enclosed spaces, or using public transport? If so then I would not expect a plane to pose a much greater risk. I would also imagine an airline would be much better at enforcing the requirement to wear masks than most other businesses.
The risk will also depend on the size of the plane and how full it is, and how long the flight is. A short flight on a big empty plane will have less risk than a long flight on a full small plane.
Ultimately it is a personal decision based on what makes you feel comfortable and safe in a particular environment, the same as with any other activity at the moment. It is not something, though, to which there is any specific added concern compared to any other similarly enclosed space.