It looks like they're using the Tab key.
After pressing the tab key, zoom in with the mouse wheel. Q makes the camera go down, E makes it go up; WASD puts the camera forward and back (W, D) and side to side (A, S). Ctrl 5-9 will also save angles.
Q is down, E is up! Be careful with the + and - keys though, they tend to distort your camera view in cinematic mode.
It's easier to set the camera as close as you can at first, then using tab+mouse wheel to get in even closer.
Pause your game while you're doing all of that so you don't miss the moment!
Press 0 (zero) to pause and unpause!
You can also use the Z key to zoom in while in TAB-mode and use the X key to zoom out again.
Be careful with the + and - keys though, they tend to distort your camera view in cinematic mode.
Clicking the left button toggles camera lock on and off.
To get a closer/lower shot you may need to change your camera view in the game settings. Using the Sims 3 camera style you can get a much lower angle.
To change to the Sims 3 camera style go to the Options menu > Game Options > Game Camera - then check The Sims 3 Camera.
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Sims 4 Camera Settings and Use (Tilt and Rotate)
http://www.carls-sims-4-guide.com/forum/index.php?topic=30288.msg486388#msg486388The Sims 4 Screenshot Tips: How to Take Better Pictures of Your Sims
https://www.ea.com/games/the-sims/the-sims-4/news/screenshot-tips-simsHow to make a video using The Sims 4
https://www.ea.com/games/the-sims/the-sims-4/news/how-to-make-a-video
