Could world wide flooding occur after both poles melt off?

The tentative answer to this is: "Yes"

I'm not entirely certain about this but raising the sea levels through melting off both poles raising sea levels worldwide by 20 to 40 feet as well as melting Greenland and the entire Antarctic ice shelf off Would allow large waves to travel great distances and do a lot of damage.

Also, Major Earthquakes of 8,9 or 10 or higher would create 100 foot waves that might carry across the oceans and go inland great distances some places. (Though if your altitude is over 100 feet normally you would be okay even then.)

As the poles melt more as time goes on many cities near the ocean are going to slowly flood. Mostly people will have time to move and the rest will drown who refuse to move. This is just what will actually happen.

So, knowing when it's time to move somewhere else might be the most important thing in all this.

Because even as the sea levels rise, still there are storm surges that are going to make the water go up 5 to 10 to even 20 feet in some cases temporarily. This is just real life for us all. So, we better get used to it.