I'm running some 6 AWG THWN wire from my main feed to a detached garage.
However the main feed panel is on the other side of the house.

Is it up to code to tap into the main feed inside the wall, go through the
attic to the other side of the house outside of any conduit?

Once I'm come out of the attic into a LB, down the wall and into the ground
it will be in schedule 40 PVC.

Thanks in advance!

Darius

From the ceiling down the wall to the main breaker, is that considered in a
raceway? Being inside the wall?

I don't really have a problem putting it into some kind of conduit through
the attic. In order to access the top or bottom of my main breaker I would
need to cut a hole in the wall to access it to get conduit in there.

A wall is not a raceway. Running in a wall would require a cable rated
for that use. Typically in a home you would use NM Sheathed cable.
Another thing I missed was the question about tapping into the main
feeds, this cannot be done. You need to install a sub panel fed from
an available circuit breaker in the main panel. I would suggest you
talk to a local electrician. This is not really a DIY job.

Don't worry I'm running to a subpanel in the garage. Thanks for the
recommendation on the ENT tubing, now I've got the whole project figured
out. I was struggling with the transition from the main breaker to the
Schedule 40, now it's a no brainer. Thanks again to everyone for posting,
you've really helped me out! Please keep on answering questions!

Good luck then. Make sure the neutral and ground bus are NOT bonded
together at the subpanel, It is a common mistake. The neutral and the
ground bus should only be bonded at the main service entrance.