Depth of field is the area in which elements are acceptably in focus. Objects closer of further away from that area will be progressively blurry.
Image from https://expertphotography.com/understanding-depth-of-field-photography/
By changing the focus and the $f$ stop (iris) on the camera, you can determine where objects are in focus and when they are not. The wider (lower value) on the $f$ stop, focus will be more critical. As you close (higher value) the iris to a higher $f$ stop more of the scene (in front and behind the object) will be in focus, or less blurry.
Here's an example from wikipedia:
Play with the values for focus and $f$ stop, until you find the point where you get the results you are after.