Just to add my 2 cent…
For thousend of years artists did made “replica” of the real thing by looking at references and do check every single working step again and again… so it looked “good”…
…so they devloped a keen eye for this and could tell you about the angle of light, the time of day/year this may took place, the position of view this was taken from, even the plants, buildings, cloth material or anything else “used” in the scene… so they could “replicate” the visual perception of the object of interest.
So for adding some object into some photo you might to ask yourself:
- are there any perspective distortions and even if not with what focal lenght was this taken…
- is the center of the original image not in the center because the image was cropped
- where does the main light come from
- are there any other light sources
- what is the day time and angle of the sun (does influence the apearance of even a white cube)
- how does the environment reflect onto itself and the object…
Finally… even when using an addon like fspy someone has to consider a lot of things… like for example mentioned in this fine tutorial:
…which may also help when not using this “helper”… to understand more about the initial problem… challenge…