I think you are referring to red giants.
Small red stars are called red dwarves. They are the least luminescent and coldest stars.
The large hot stars are typically called "blue-white" stars or also Blue Giants. Cooler large stars are called Red Giants.
Yes red giants are the largest. But the bigger stars of red giants can be called red hyper giants.
No blue stars are the largest and brightest stars know of. (They are also called Hypergiants). Red giants are dimmer.
If they have red stars including giants in, they can't be all that featureless.
No, red dwarfs are called such because of their reddish color. They are the coolest of the main sequence stars. Blue stars are the hottest.
In astronomy, stars of spectral type M (the stars with the coolest temperature) are classified as red stars. Mars is called the Red Planet because of the reddish color
We cannot locate a film called Red Ocean. Maybe you meant Red October? It is about a submarine and stars Sean Connery. Or possibly Red River? It is about a cattle empire in Texas and stars John Wayne.
They are red giants.
With red giants and main sequence stars they are not entirely featureless, therefore there is no name for them.
Red giants.
Correct. M-type stars on the main sequence are called red dwarfs.