Of course, it is possible, and we have some users regularly posting their works in the Artwork-Categories of this forum.
Krita itself has a few pixel-art brush presets and there are more to get in Brushes and Bundles, which is a subcategory of the Resources-Category.
You must obey that the smallest unit you can use in pixel-art is the pixel, so 1 single dot, this means, you have to plan before you begin your works and ask yourself: “What is the smallest thing I want to show in my work?”! Depending on your skills in composition and planning, it may be a good idea to begin with this tiniest thing you want to display. And to see your pixels on canvas, you just need to zoom in, more and more until Krita will show the canvas to you full of squares, these are the pixels you will work with. When painting slants you will see no clear line but stairs, that is an unavoidable effect (Unless you go up in size and put every single pixel on a canvas of 2Mega-Pixel, which can be viewed like most pictures posted in the forum, to create a large image “Impressionistic” with pixels. But I’m sure others know better than I do, and whether this is common or not).
Here you’ll find an example of over 8 mega-pixel, in this one you can see the stair-effect very clearly, even animations can be found in pixel-art like this one, or this, or this masterpiece.
In principle, you are now ready to begin, maybe you want to watch some tutorials on the topic on YouTube beforehand.
Michelist