This is some short instructions on how to make a small object like a toy car look like a full life sized one.
Step 1: Camera Settings
The setting on the camera most important to achieve this is called aperture. Aperture controls how much the background of your picture is blurred. For this we will need a very high aperture to ensure the thing that is close to the camera looks almost the same amount in focus as the things in the background. On my Canon Rebel T6 the AV setting gives you the most diverse settings with aperture. You will need a large aperture to bring the background into focus. This may also be expressed on your camera by an F then a number.
Step 2: The Small Object
The small object that you are taking a picture of can make the difference between having a convincing photo and people noticing you're up to something. The more detail you have on your object, the better the picture will look. In my case the toy car looked pretty good but if you look harder you can see that the hood scoop is a bit messed up. What I did to counteract this is I took a side shot so that you couldn't see it. Angles matter a lot.
Step 3: Blending Foreground and Background
The hardest part is the ground that the object is on as well as the angle. I simply used a concrete slab to act as the ground both of the cars were on and angled it to look like they were parked side by side. I parked the real car back far enough that only the toy car would be on the concrete slab. I was having an issue with the corner of the slab looking a little too out of place so I also rubbed dirt on the sides to make it blend with the background a bit better.
Step 4: Perfect Focus
The last step is getting the focus right. If you can't seem to get both objects perfectly in focus I would suggest getting them both the same amount out of focus to make the depth of field feel the same. It is a bit of trial and error but the end result can be a very cool and deceiving picture. With this trick you can do anything from tricking your friends into thinking you bought a new car to making giant monsters in a stop motion animation.