Hi, I don't know much about java, so I decided to write to you here. My friends and I want to increase the number of pixels on the canvas. If it's not difficult for you, can you tell me how to do it? And is it even possible? Thank you.

It would be possible but not as easy as changing a few variables. If you want a bigger canvas with more pixels, you would need to update the painting GUI, the canvas entity, easel rendering, possibly saving-loading, etc. You can check out the source code for details.