Do I need unity 3D for game card

Question

I'm a flutter developer, and I want to begin a new card game that we play in my country, but I saw on internet that flutter is not really appropriate for game. So in my research I see unity 3D, I want to know if flutter can be a good solution too, or it will be better for me to made it with unity.

PS : I want my game to be a multiplayer game, like two real person can play one against the other.

Thank for reply