In D&D5 multiple sources of advantage, resistance etc do not stack.
For example if you have multiple sources of advantage but one of disadvantage they cancel each other out.
Likewise resistance stays resistance and doesnt get any better. Unless you can gain immunity.
However as mentioned Warding Bond works on top of that.
Another ability that works on top of incoming damage is the Uncanny Dodge of Rogue 5+.
Theres also the Abjurer special ability, however that one gets better with Wizard level.
