Best isolation exercise for arm symmetry?

[RebornGC45]

I've been doing compound movements and a beginner program and I've noticed some muscle imbalances especially in my tris and bis...the problem is I'm right handed but my left side is out growing my dominant side completely. Also I noticed that my left side has a way tiggter skin and it feels 3x more firm than my riggt arm. The skin on my right arm is wrinkly and sagging especially near armpit and lats while my left skin is tight as fudge. It's especially noticeable when I wear shirts. It's as if my skin is not holding the stuff inside my right arm properly. Like the elasticity or thickness of the skin is gone

[k9pit]

Not all of us are 100% symmetrical and ingrained motor patterns from other non-lifting stuff over the years can cause you to natively make little adjustments in your activities to work around weaker or less coordinated muscles. This can transfer over to your lifting also.

With that said you can do your arm training with dumb bells or using machines with one arm at a time. Just make sure you don't allow your shoulder on your weaker arm to take over and overcompensate for that weakness. Isolate and build the muscle up.

DB Curls.
DB Skullcrushers.
One arm Pulldowns.
DB Kickbacks..
Machine preacher curls with one arm

[RebornGC45]

What can I do about my skin?

My left arm has way tighter skin than my right and my left feels so much more compact and firm. I can't even pinch my left skin at all compared to my right. It's hard to describe it in words but my tricep pm right literally sags and all wrinkly while my left seems more youthful lolol

[RebornGC45]

Major bump sorry