Take this song for example... https://youtu.be/cyOqIKGbYkg
He uses both chest voice and head voice, the first few lines he sings in definite chest voice. Then when he starts singing, "and all I can taste is this moment..." - this seems to be in a middle register, although I would liken this more to the chest voice because he's still pushing from the chest. But then when he sings the line, 'when everything feels like...', he is definitely singing in the head voice. There is a clear break in his voice. You will have noticed that clear break between your head and chest voice while singing.
Two exercises I would recommend to try and figure out how to achieve different things with your own voice is this:
Pick out one phrase such as 'and all I can taste is this moment', which is more ambiguous, and try to sing it in both head and chest voice. You might find that neither of these feel the most natural. When I tried it, there was a definite middle register that felt the best, and this was when my throat relaxed more, but still using support and pressure from the chest area. My head voice sounded much weaker and less nasal. See if this is the same for you.
Another exercise to try is a simple one:
This involves controlling the 'break' between head and chest voice. Pick a scale in your mid register and purposefully choose where it breaks into your head voice. It is possible to make the break happen on each and every note of the scale. For example, here's the middle C scale:
C-D-E-F-G-A-B-C : I can first sing the whole thing in my head voice. Then one by one (C first, then C to D, then C to D to E, etc) I will sing in my chest voice and then continue in my head voice. This will build up a strong foundation for control. Singers, especially pop singers use a wide variety of colours in their voice, and part of their success at doing that is having the ability to mix blend and control their registers.
Hope this is helpful! Good luck! :)