Here are some of my suggestions on why I think Yebba’s vocals are so good! I think modelling on a great voice like Yebba’s is fun, interesting and is a nice break from just running scales and tuning vowels.
The purpose of modelling on a great voice is NOT to sound like them but just to learn from their musicality and resonance strategies. You could even go as far as trying to perfect your best Yebba impression, this is great for increasing flexibility in your instrument but you should always let things settle back to a more natural way of singing for you!
As always, be aware of what feels and sounds good to you and have fun with your singing practice. And please love your own sound, as Oscar Wilde said – “everybody else’s sound is taken” … direct quote.