In general, no: one fixed lens hood will not work well for both lenses.

Lens hoods are shaped for a lens’s angle of view. A wide lens like 18mm needs a much shallower hood so it doesn’t appear in the frame, while a telephoto like 300mm can use a much deeper hood because its field of view is much narrower. A hood that’s ideal at 300mm would likely cause dark corners or obvious blockage at 18mm.

That’s also why hood shapes differ: telephoto hoods are often round, while wider lenses often use petal-shaped hoods to maximize shading without vignetting.

If you want one flexible option, it has to be adjustable rather than fixed—examples include collapsible or flap/barn-door style hoods. These are compromises, though, and usually not as effective as using the correct hood for each lens.

A simple no-cost alternative is to shade the lens with your hand or another object, as long as it stays out of the frame.