Used to draw in 16x16, how to draw pixel in bigger size?

First of all, please apologize my broken English. I've been using aseprite for two years now and usually I work with small size 16x16. I don't dare to work with bigger size because the outline will be so small (with 16x16 size, the 1 cm outline is perfect), and if i use bigger outline, it doesn't look pixel anymore. it looks like line with bigger outline.

My explanation might be unclear. I can send the picture on comment section once I'm with my pc!