View Settings is a quick way to see the global preferences you have enabled for the Editor. You can select or deselect from this menu, or use the keyboard shortcuts.
In Figma, this can be configured with a scale factor of either 1 (1 virtual pixel on the grid = 1 pixel rasterized), or 2.
Select the canvas (press ESC a few times) and find it in the properties panel. You can also toggle pixel preview on/off using the keyboard shortcut Control + P.
Show Pixel grid
Because your operating system as well as your browser affect what "1 pixel" actually means in terms of hardware pixels on a particular display, pixels in Figma are really screen points, or virtual pixels. This means that the pixel grid has vertical and horizontal strides that are exactly 1 virtual pixel. Changing that would mean the pixel grid is no longer a pixel grid, and for these situations it's really a lot easier and better to use Layout Grids on a frame (frames can be really large.)
Snap to Pixel Grid
If you have Snap to Pixel Grid enabled, and zoom in really far, you'll see that objects on the canvas should snap to the grid. They should not end up off-pixel unless you manually adjust it's properties.
Layout Grids are configurable in the properties panel sidebar with a frame or component selected. You can add add vertical and/or horizontal grids and the can be configured in a number of ways.
If you have this enabled, you will see the cursor movement of anyone your simultaneously collaborating in a file. If this gets too noisy you can always disable it.