Any Copywriting Buffs?

Hi guys!

Looking for some professional opinions/help.

Basically, I'm going to apply for a Copywriting Assistant job. Experience isn't essential and they offer some training, but they've suggested I write a bespoke cover letter to showcase my writing skills.

I've got a bit of knowledge in Copywriting, but nothing major. Is there any guidance or tips you guys can offer?

Always appreciated!
I would recommend identifying certain thematic areas and working on them in detail to gain some knowledge. I do not recommend writing about everything.
Research the company, establish gaps in their current copywriting and then write how you would bridge those gaps for them, in a personable, conversational manner. That's how I'd do it. Hope that helps!