To be honest it’s extremely common to see people looking for Anki decks and stuff like that to build vocabulary…
But there might as well still be something a bit wrong in that approach despite all the people that do it…
The thing is, once you know your very basic core vocabulary (true basic core vocab is more like 300/500 perhaps 1000 words, but don’t go learninf “core 6k”… anyway so you already have that basic core vocab),
the rest of your vocabulary should preferably be learned from immersion. Precisely, watch anime (or other immersion material if you don’t like anime) on Animelon with japanese subtitles, and use yomichan to check words you don’t know, and if they’re common enough (I recommend having the “Anime and JDrama Frequency list” dictionnary enabled for that), click to automatically add them to your Anki thanks to yomichan.
Why is it better ? If you want the explanations in their best form, I recommend simply watching these 2 videos by Cure Dolly : Japanese Core Vocabulary: how to acquire it (and how NOT to!) - YouTube (part1) and Japanese Core Vocab the Smart Way: Full instructions for strategic Anki use - YouTube (part2).
Basically, it’s important to jump into immersion as soon as possible, but over that, you’ll be learning vocabulary much more organically and will have experiences to rattach the word to. Also, by learning from anime, you’ll learn the words that truly are common in anime, since you learned it from anime directly (i don’t think you would like to learn the 3k most common words in newspaper for example). You’ll be learning kanji as parts of these words too.
(watching anime with yomichan is more fun and useful than diving into Anki decks (or WaniKani, as you can see I’m level 3 but I used to have the subscription. I decided to resign for basically the same reason I told you. So what I’m telling you is not an imaginary strategy. I decided to quit WK because I strongly believe that that approach is indeed better.)
Alright, so what I recommend for you is to watch these 2 videos to learn more about the topic of what you asked here.
If you don’t know about Cure Dolly yet, then I would be very happy to bring her channel to you. Seriously, it TRULY IS a game changer. Go check even her first basic videos from her main playlist, because you’ll sure be learning stuff anyway : Lesson 1: Japanese made easy! What schools never teach. The core Japanese sentence -organic Japanese - YouTube
If you have any questions about anything, please ask and I’l try to answer my best about everything.