If you’re using a headphone amplifier + headphones or an amp with speakers, there will be some variations in loudness between songs from different Artists.
Ideally, 60 db to 70 db is safe for several hours of listening. If you get listening fatigue and/or a headache in the first 5-10 minutes, you’re doing something wrong.
The only time you should listen a bit louder is when you are mixing/mastering something. Even then, for a short time - to ensure you can detect errors in the sound and fix them.