Hmm, I've read this article about mixing out of key songs and making them "in key" for the next track, opening up what song can be played next. It takes away the worry of whether or not the vocals or melodies will clash and sound awful.
It's quite the read, so make a brew before you sit down.
https://www.digitaldjtips.com/2021/01/f ... way-to-dj/
