You are describing a deluge, end of times. Not a rise in sea level.
"Since 1994, the islanders of the seven atolls, lying only 1.2 metres above sea level, have already lost about 50 per cent of their land. Traditional food sources have become scarce, regularly placing the islanders in situations of near famine. The communities also face severe water shortages due to prolonged droughts and sea-level rises that affect their freshwater supply." [2]
[1] https://www.newscientist.com/article/2146594-eight-low-lying...
[2] https://www.resilience.org/stories/2019-06-11/understanding-...
But how is this "many people will die"? Have people already died? Are they dying by the 100ths? Or the thousands?
I guess not. And they will migrate away.