Add multiple images to a project(Character Design)

Is there a way to import different images to a project?

Like if I have a project with 128x128 resolution and I want to add a bunch of images that have 32x32 resolution in there. Is this possible?

Or the only thing I can do is design the character with all the frames in the same project and then use Aesprite to generate a spritesheet?

Thanks,
Nour