You're using RPGMaker? You will need to scale them by 3 so they're 48x48, then in another file make them fit into the rules for the engine. Follow this tutorial: https://www.youtube.com/watch?v=1Vv-lokCGr8
And here are the rules for rpgmaker mz: https://rpgmakerofficial.com/product/MZ_help-en/01_11_01.html
I hope this helps