i dont have the game yet ( got delayed ) but i have played it, i do have alot of the expansions. i noticed that the larger ships come with 2 stress tokens. i read that it takes 2 ion cannon shots to take effect so here are my question

do larger ships or any ship able to get more than 1 stress token?

Stress tokens affect large ships in the same way that they affect all other ships. They do not need an extra one to have an effect like ion tokens do. There are multiple ways that a ship could end up with more than one stress token. This is allowed. There is no additional effect for having multiple stress tokens, but only one is removed with each green maneuver.