Star Key is an Itailan animated series, it has 26 episodes and appears to have aired in Italy in 2018. The art style is very anime inspired and was collaboratively worked on by Gama Movie Animation S.r.l along with various animation studios such as SEK Studio, who also worked on one episode of Avatar the Last Airbender. I can’t find that much information about this show or any full episodes online. There also doesn’t appear to have ever been a DVD release.
Found a Facebook page for Star Key, which then led me to a place to watch the series on a website called raiplay. Unfortunately you need to live in Italy to stream it, so I cannot actually access any of the episodes.
With some more searching it seems that someone on YouTube very recently uploaded all episodes of the series. I don’t know how long they will be there, but they are all up as of posting this.