Elle here from Shopify. I've moved your post from our Technical Q&A board to the Design board as you'll likely receive a better response here!
You can do like that for select box with font style preview
<select> <option style="font-family: cursive;" value="cursive">Cursive</option> </select>
Note: add your all font like that
You can add this select box where you want it. You have to add your font option that you want i have added just one for demo
As i told you have to add all font that you want in <option> as i have added one.