The beauty of Freelance is that you can write whatever you want! 
I always suggest to newbies that they make their first “job” their own portfolio.
First: find a local business to you with awful landing page text (typos, boring, too short, etc) and rewrite it. Swap out any mention of their name as “X Company Plumbing” or something like that, something that makes it obvious it’s a placeholder. THEN (this is the important part) take a screenshot of the work - shrink it down on your screen with ctrl and - buttons if you need to in order to fit more in the shot. It’s okay if it’s not the whole thing, this is just for your portfolio. (Do a before/after screenshot if you want to do an editing gig)
Then, write a 300-ish word article/blog about something you love, but do not use first person (e.g. “I” / “me”). Very few clients want anything written from the first person perspective so you don’t want to have that as your example, and by writing something you care about, your passion and word choice are going to be more thoughtful and well-formed by default. Give it the same screenshot treatment.
Then, go on Amazon and - just like with the local business thing - find an item that’s written very poorly / obviously foreign and poorly translated, preferably an item you’d actually want to buy, because again, it’ll shine through in your work. Give it your treatment, take a screenshot. (Do a before/after screenshot if you want to do an editing gig)
An afternoon of work and you’ll have a nice minimalist “Fiverr Portfolio” set of pieces that you can add to your gigs. 