Airplane Travel bags for bikes

Planning at least two trips this year a need a bike bag for a plane that doesn’t cost as much as a new bike.

Ideally, fits my gravel bike (Kona Unit X) and also my MTB (Carbon Specialized Stumpjumper). Emphasis on carbon because I worry that it could get damaged.

Bonus points if it can also fit things like helmets and paniers and racks whatnot.

Any experience?