My character size is big enough but it seems so small on the screen. How to fix that?

My characters pixel resulation is 64x64 and it is enought for pixel draw. But in the screen everything is small in 1920x1080 res. How am i able to make them look big?

SpriteBatch.Draw has a scale parameter for that.
If you want your entire game to look retro-style pixelated, work with a lower resolution than 1920x1080.

As mentioned, use the scale parameter of the draw method, or use a lower resolution such as 640x480, or 720p, 960p, or 768p for that mid 90’s feel

Or………

But when i do that , people play only at that res. Isnt that?

This may help

Most retro looking 2D games use a fixed resolution that everybody plays at.
I’m talking about the resolution you draw the game at, not the resolution of your game window. The game window can be a higher resolution.

This is done by drawing the game into a low resolution render target that gets scaled up to cover the game window in the end. You just have to make sure to scale by integer values only, to preserve pixel-perfectness, which means you may need to introduce black bars.