[PS] Witcher 3 Remastered DLC 2.. Was the completion DLC?

I'm in the middle of DLC 2, Blood and Wine.. Suddenly a little kid runs up.. saying Yennefer left a letter.. It's a letter from Yennefer.. I couldn't just pass it up.. so I read it right away.. It says to find a professor who was researching the Witcher's mutation factors.. Well, I decided to follow the quest to change the mood a bit.. But what do you know.. On the way, I had to go to the Drowner's nest.. but the Drowners were level 40.. My Geralt is level 38, and I got cut down in 2 hits.. After drinking the Drowner-repelling potion and going in.. Wow.. Even though it's a sub-quest, CDPR really put effort into the story and cutscenes.. They're a god-tier game company.. Turns out you can further enhance the mutation factors.. At the end, I had to fight 3 giant centipedes, which was easier than I thought.. After finishing the quest, I got Enhanced Synapses...? It's like the Steel system in Fates of the Old Republic.. Was this always there..? I realized I quit Witcher 3 without properly playing it.. I guess I should meticulously complete all the remaining quests.. I'm debating whether to buy the new DLC on Steam..