Applying for a job writing, should my cover letter be in the same style they would want me to write?

I'm applying for a job on a travel writing/review website as a food reviewer. Basically I would go to a specific destination, try the food, take some photos and then write about it for the websites' blog and/or youtube channel.

They mention more than once in the job description that they want someone who can write in a conversational/casual tone. When writing my cover letter, should I use a polite but conversational tone? Or keep it strictly professional?

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