Are IV fluids effective for the flu?

Among those who have tried it, some say the effect is immediate.
While there are quite a few people who highly praise it,
the information I received from a local internal medicine clinic was different.
According to the specialist there,
"If you are able to eat meals orally, there is no need to get IV fluids."
After saying that, he just prescribed oral medication.
In other words, according to the doctor, IV fluids are only necessary for patients who are so ill they can't even eat porridge, right?
As a side note, when I had a cold a few months ago, another hospital prescribed IV fluids right away without any oral medication,
but to be honest, after getting it... I'm not sure. It's ambiguous.
Whether this is actually effective or not,
it feels like half a placebo effect.