I'm thinking you mean like give a person like a diamond sword ànd a diamond helmet instead of what the guy above me said. There's a way to do this by summoning an activator rail on top of the commandblock with a commandblock minecart on top that'll run its command. This way you can add multiple commandblock minecarts and thus multiple items can be given with one commandblock. Here's the catch though: It's kinda difficult. So if you really want to give a player multiple items, I suggest using multiple commandblocks. Hope this was helpfull!
The variant with the riding items does work if you use the Owner tag.
Owner: If not an empty string, only the named player will be able to pick up this item, until it is within 10 seconds of despawning. Used by the give command (and can be set in a summon command) to prevent the wrong player from picking up the spawned item entity.