The default texture size is 2048X2048. Textures larger than this will be downsized to the default upon import. To increase the maximum size, go to File/Preferences in the Element Scene Interface, and under the Map Size Limit drop-down, it can be increased to a max size of 8192x8192. Texture may need to be re-loaded to be increased to max size.
Increasing the Map Size Limit will utilize more system resources (GPU), so be sure you have enough power or Element 3D and/or After Effects may become sluggish or unresponsive.