Anim starter pack equip and no equip

Hi, I am trying to make a third Person Shooter. I retargeted third person character stuff to Anim starter Pack but I want to achieve like when I am having gun it should pose like and with out gun character should be normal is there any easy way for this.

I know this is kind of easy but I am new to these animations and things please help me

I don’t want to change anim instances every time as it is not looking good