Change minimal anchor sizes

[kimalaacer]

My object to be detected is very small, single class, and will never exceed 40 * 10, 10 * 40, 7 * 7 pixels in size.

Now, the prediction boxes are accurate in detecting the object, however, they cover 75% of the input image.
is there a way to force a prediction box to a max size of 40 * 40 pixel?
I Know that the biggest anchors are set to 32 X 32 in efficientDet.
Is there a way to change them to 6 X 6 (or 10 x 10) to make sure my objects are detected?
Thanks,