Will upgrading to 16GB of RAM fix my Warzone stutters?

Yes, upgrade to 16GB. Your 5600X and 3060 are fine for Warzone — 8GB of RAM is the bottleneck. Warzone easily eats 10–12GB during a match, and with only 8GB, Windows swaps to disk, causing micro-stutter. Go dual-channel at 3200MHz or faster.