a general rule with RPG maker starting from at least VX is that normally a sprite file is divided in 4 by 2 sections . each section is a 3 by 4 sub section.
Here’s a visual of that:
now this is default and each “actor” takes up 1/8th of this file using the 4 by 2 rule.
now the interesting thing here is that there is NO limit to how big this file can be.
this being 384 x 256. but nothing is stopping you from using double or more the file size, you can go as big as you like. as long as it can be divided using this 4 by 2 rule.
one thing to consider however is of course file size and storage it uses and if you sprite is too big it may cover the entire screen making it hard to navigate around the maps.
the reason i bring this up is you don’t need a particular program to make bigger sprites. you can make them manually, but there are for sure resources out there that help you get started. one example being this one
also in case you don’t know. adding a $ before a file makes RPG maker treat that file as 1 entire 3 by 4 section regardless of size. this is often used in RPG maker for very big sprites to save data.