Hi zalabinc,

Please go to the project settings, switch Perspective to Orthographic in Camera Settings. The camera setting decides the viewing method of the camera.

Perspective: This method shows the Z-depth relation of each item inside. The size of the objects, in theory; alter automatically in accordance to the distance of the item.

Orthographic: This method shows the project regardless of the Z-depth of each object inside. This method is used by most image editing software since Z-depth is unnecessary for them. Therefore, the size of each object looks the same even if it is far away from the camera.

Alllen
Reallusion