I am using Gimp or Krita, I'm learning to use them yet, thanks for the answer, I'll search more about it.
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In Gimp you can use "Image" -> "Scale Image..." and then in a popup window choose "Interpolation" to be "None" and resize e.g. 300% or whatever you like..
In Krita you can use "Image" -> "Scale Image To New Size..." and then in a popup window choose "Filter" to be "Box" and resize e.g. 300% or whatever you like.