Are nebulas actually all those bright colors?

They've been enhanced. The colors are not that far off from their true colors, but the human eye is not sensitive enough to see these colors. Photographic imaging brings out colors that are too faint to be recorded by human eyes.

In addition, many of the images are shot in greyscale 3 times with colored filters and then are combined with colorization. The filters correspond to the common emissions of hydrogen, oxygen and sulfur.

Some of the nebula images are real colours.  Nebula can refract and reflect starlight.  They can also absorb ultraviolet light from stars and re-emit that light as red "emission" nebula.

But some images are computer-enhanced to increase contrast to bring out details.  And some are taken in different wavelengths to bring out extra information that is not visible light.

But none of them are computer graphics - they are not "created" by computer the way a movie or video game is.

The nebulae really are those colours, but you can't normally see the colours with your naked eye. All of the pictures of coloured nebulae are long time exposures to bring out the colour and detail. But the human eye is not sensitive to colours in dim light, so all you will see 99% of the time through a telescope visually is shades of grey, some of them exceedingly dim. The miracle is that we can see them at all with our very limited eyes.

In 50 years of observing, I've only seen colour in nebulae a few times, mostly with very large apertures (18" and up). You can see colour in the planets and in stars, because they are relatively bright, but not in nebulae or galaxies.

if a picture says it's true-colour, then yes, the colours are real. except that, in this case, "real" means what our eyes would see if they were millions of times more sensitive to light.

our eyes are most sensitive to green, so if an emission nebula shows any colour at all, it's a hint of green (the orion nebula is a good candidate for this - with a big scope and dark skies). our night vision is primarily in black and white.

NO!
If you use a telescope,
all Nebulas are color black and white!