The phrase "as a key theme" is correct and usable in written English.
It can be used to highlight an important or central idea within a discussion, analysis, or narrative.
Example: "In her novel, the struggle for identity emerges as a key theme that resonates with readers."
Alternatives: "as a central motif" or "as a primary focus".
That said, devolution is emerging as a key theme of efforts to revamp state government.
In the closing days of the Iowa campaign, experience has re-emerged as a key theme.
What YA novels have you read that have included poems or poetry as a key theme?
Designers took note, with Brexit and ideas of Britishness emerging as a key theme of the collections.
It has emerged as a key theme in the evaluation of the project, with both intellectual and emotional reactions stimulated through relatable stories and locally commissioned work.
Engineering the spatial organization of biochemistry has emerged as a key theme of synthetic biology, with numerous technologies promising improved biosynthetic pathway performance.
However, relations between India's 150 million Muslims and the Hindu majority, as much as development, was a key theme as candidates traded accusations of seeking to win votes through targeting particular communities or raising sectarian tensions.
Finding a way to mitigate the impact of these digital transformations on workers as well as businesses was a key theme of the May 24 MIT Sloan CIO Symposium.
One of the two SCP thrusts was tackling high volume crime such as domestic burglary, where a key theme was to develop local infrastructure and skills to identify the nature of different problems.
Social sin, as it is called, was a key theme of John Paul II, and one of many areas where the two men shared similar views.
What he can commit to is that procrastination will be a key theme (as it was in The Victorian in the Wall), and that it's his most personal show yet.
