Of the 3 domains currently provided only 1 can use heavy armor, and of the 7 in the PHB only 4 can, so just over half. Your assignation of the "tank" role to cleric is just that, your assignation. They certainly CAN be played that way but by no means is it "meant to." Trickery domain clerics are closer to rogues and Light are closer to mages. If you do want to infer what is intended however, you can simply follow the PHB suggestion that wisdom then charisma are the primary attributes for a cleric and then utilize the standard array. You won't have a cleric with a +2 DEX modifier in most cases though. Also, as you want to lean on starting equipment to infer intent, then clerics are meant to value STR over DEX as well based on their starting weapons.
All that said... classes, in general, are nerfed of their individual specialties by Larian's implementation of the game world. It is pretty clear from their previous games they dislike class based systems and they are making every effort to eliminate class from this one too.
