It`s Possible But depends on which method do you want to use
you can use Either a Dummy unit with 6 slot inventory which is moving with you hero you can add Worker flag to it so you can access to it via F8 or you can use multiple hero`s as bagpacks you know they are accessible by pressing F2 ,F3, F4 Keys it is a simple system you can always have 30 slot available have you played Shuken City map? it uses the same System
you can use an alternative but very complex system like
this one
which is very fancy made system it looks gorgeous but to be honest with you i couldn`t use it because you should create A UI for every Hero which is not practically possible in a multiplayer map anyway your choice