Please i am a beginner i need more flat routes in 20-30 km range as i got bored from the watopia route
What kind of trainer are you using? You could just turn the difficulty down to 0 and pedal for the same amount of time on the shorter routes.
That or get better at riding!
Or lower your weight way down so hills don’t impact you as much.
Flat routes are known to be the most popular. Regarding routes though, just get on and ride any route until you have ridden enough for the day. There is no reason to feel like you have to finish the route. Also, if you want everything to feel flat you can turn the trainer difficulty to zero (try 30% first before you turn it completely off though).
There’s flat and flat though. Some of the non-Watopia routes have minimal climbing.