You can lock a attribute (str, dex, con…) and select a perk when using a Timeless Shard (check tradepost on your server) which drops since the latest patch.
Also worth noting, this is a huge improvement over the old system. Before you could choose either a perk OR an attribute. So if you picked dexterity, you risked getting bad perks. If you picked a good perk, you risked getting the wrong attribute.
Now you can use timeless shards to pick one perk and one stat
At the outfitter, arcana or forge check out the genesis and lazarus replicas. Some have a locked attribute (genesis heavy armor always has constitution) and let you still select a perk BUT those replicas require a specific crafting material dropping in the corresponding dungeon (sticky vines for genesis armor).