real case:So take +2 plate and a +3 shield (very rare items). You are now at 25 AC before buffs.
Add in a +2 buff of some kind (Shield of faith? Haste?) and defensive fighting style, and you have 28 AC.
Add in shield, and you hit 33 AC.
Creatures that hit 21-25 AC A LOT ... won't ever hit this.
Even if you roll it back to ; +1 plate and a +1 shield; 22 AC base. +2 AC self buff and defensive; 25 AC. Then 30 AC with shield. 1 rare item and 1 uncommon item, neither attunement, which isn't atypical for a level 8 PC (although both are defensive).
At the extreme, toss a cloak of displacement on top of this.
A paladin/Warlock with +2 halfplate (with a house rule material it was made of) and a +3 shield (DM random rolled, and learned why we don't suggest such) and the defensive fighting style, was allowed to spend money by having a mage make them magic items... they got a +1 ring of protection and a +1 cloak of protection, 27 AC on all the time. even without SHIELD (that would be broken on this girl) they were all but unhitable.