Pseudo-giantess

Considering that prefix "pseudo-" means "false/fake", then a pseudo-giantess becomes a fake giantess. That is, it is about a being that although it seems to be a absolute giantess, it really is not.

There are several cases in which pseudo-giantess can be presented, let's see:

Para-giantess: Interaction with shrunken or miniatures
When a normal-sized woman interacts with beings smaller than herself:

Para-giantess: Interaction with chibis
When a woman interacts with chibis, who are usually smaller than normal:

POV
When you see a woman from below, giving the feeling that she is bigger:

Forced perspective
When the position of the objects generates a false appearance of giantess:

Interaction with Objects to scale (toys, figures, mock-ups)
When interacting with models, toys and the like:

Stretched Images
When you stretch the image of a woman because of the presence of a large screen or a huge advertising poster:

Mecha musume
It is a particular case of gijinka and mecha, where women in manga/anime style are representation or personifications of weapons or military equipment.