Rest and fluids, then let your body do the rest.
I’ve had flu twice, once when I was a kid coming back from holiday (don’t really remember too much about it).
Second time was a few years ago, I was flat out for a week, wiped for for another week and then eventually went to the docs at the end of the second week because i still felt pretty bad and thought it must be “something more serious than flu”. The doc had a bit of a chuckle, making the point that flu is so misinterpreted now and that flu is really serious. He told me to go back and get more rest.
Think it was about 3 weeks until i was well enough to walk to the local shop etc.
To be fair, i was pretty run down when i picked it up, but regardless, plently of rest and fluids 😀