The preview size and direction of the block are controllable

Rhino
1

a1
a11334×630 128 KB

a2
a21224×611 111 KB

a3
a31547×893 255 KB

2

Hi -
In Rhino 8, you can set the view and the display mode for this preview:
image

-wim

3

Very good. It would be better if the thumbnail could be enlarged