How can I make the game Screen to fit resolution

So I'm here wondering how I can simply make my game screen to fit the different resolutions. I used (new Rect(Screen.width/2.5f,Screen.height/1.73f,Screen.width/5,Screen.height/10) at the menus and it worked perfectly. But the problem is that the game screen has a first person view with it is holding a sword. But you can't see the sword if you are not in a aspect ratio of 16:10 or lower. The height has to be lower than the width * 0,625.

So if you are using a resolution that is 1366x768, then you have to make sure you have a height lower than 1366 * 0,625, which is 853, which works fine. But if you got a screen like 800x600 then your height will be higher than what you get as result, and that means you can't literally see the sword. If anoyone could lend a hand, I would appreciate it!

Edit: Here you go 1366x768

800x600