One of my favorite forehands belongs to former ATP pro Lukcas Lacko. His forehand, with a fairly straight arm and simple takeback make it a great model. This rear view of his forehand shows the slot, the pulling action, and the inside out path of the racket perfectly.
The animation on the left I call "popping the cap". The butt cap of his racket starts pointing inward towards his body. Then he "pops the cap" by twisting the hand backwards, internally rotating his shoulder, and pulling forward. This gets the butt cap to "pop" and point out towards the incoming ball. His wrist is fully laid back and at a 90 degree angle.
By popping the cap, he can pull the racket through the slot. The butt cap of the racket continues to point to the incoming ball as he pulls the racket towards the ball.
Moments before contact, Lacko will release the shoulder (external rotation), wrist and forearm muscles, causing the tip of the racket to speed up in an inside out path into the ball. His wrist will only be laid back about 20 or 30 degrees on contact.
Lacko's forehand really shows how the stretch shortening cycle works in the modern forehand. Here is a definition of the stretch shortening cycle:
The stretch-shortening cycle (SSC) refers to the muscle action when active muscle lengthening is immediately followed by active muscle shortening. This combination of eccentric and concentric contractions is one the most common type of muscle action during locomotion.
In the case of the modern forehand, the stretch-shortening cycle comes from laying back the wrist, internally rotating the shoulder, and pulling forward. This causes the shoulder muscle and forearm muscles to lengthen. Then right before contact you relax them and they shorten, causing the racket head to whip around, inside out.