voice and judgement are two different things
I feel like you don't need to make a conscious effort in order to implement personal voice, it just shows in stuff like your thesis, analysis and expression. every student has a unique voice without really trying, unless they're plagiarising or something
when it comes to personal judgement you can show this in your conclusion, my teacher always recommended some type of evaluation in the conclusion using evaluative adverbs like [interestingly, ironically, consequently, surprisingly, unfortunately , remarkably, paradoxically] etc.
also evaluative statements or sentence starters like "Consequently, we see in today's world..." or "In light of this, we are led to consider our own..." or "...the composer reminds us of the importance of..."
if you show judgement in your conclusion or even throughout your essay it shows the marker that you personally engaged with the text and that you have your own opinions about it, objective analysis alone isn't usually enough for band 6
I have a doc on evaluative language with more examples than the ones I gave, if you want it then lmk