Both landscape and portrait aspect ratios are supported.
If possible, it is best to depict only the face and upper body. (If used for inpainting, anything is possible.)
There are no issues when using Illustrious' default supported characters, but when using the other character Lora, the character's priority is high, often causing it to go out of the frame. Please increase Lora's weight and place the trigger word at the very beginning.