Hi everyone!  Just a simple question.  I've come across these types of focal length perspectives in fashion images/fashion lookbooks often and I need advice on what focal length lenses these are?  Where the feet (or hands in some other photo examples not tagged here, are really large and the head is tiny).
What kind of position I'd need to get in to get real low to the ground looking up perspective?  I'm assuming i'd need to lay on the ground?  Anyways thanks in advance to anyone that can help me! 

Link to example images: https://imgur.com/a/AbSr3NB

It's simply a wide angle lens.  Depending on the camera it's most likely 18 to 28mm (or equivalent)

It's the same technique that I used in this photo:

Hope this helps
http://www.stepheneastwood.com/tutorial … ective.htm

I'm wondering if an ultra-wide angle lens can do that.  Just picked up a Laowa 12mm 2.8 Zero-D and I think it can do something like this.  Here's what someone else did with it:

I’ve done this mostly with a 24mm, but you do need to get close to the part you are enlarging - don’t be timid!

If I were using and ultra wide, I might back off a little.

12-17mm probably f8 or above.