Itās nice to have it done automatically. But 600x600 is really low quality. Unfortunately the Rose streamers donāt really support larger formats but 1500x1500 is what you would want to go for as a standard.
I have made covers professionally so I know what Iām talking about. And remember that 1500x1500 does not mean a large file size if itās a jpg saved by a proper image app. These file sizes are negligible compared to a lossless music file.
I do advise, if you donāt like the cover quality, or itās not the correct cover, just Google it and choose āimages>tools>largeā. Often Amazon has the best.
When the music is old-school I like to get the original LP album cover, maybe some wear on it. It takes some clipping, straightening, color correction. But then it looks more authentic. When it comes to modern albums some covers are really high res (Bjƶrk for instance). Then I scale them down to 1500 or maybe 2000. File size hardy ever exceeds half a MB.
I do this all on my phone. Itās about a minute per cover. Then tag the flacs with the covers inside (remove doubles). But then I get them the way I like it. And you only need to do it once.