Oppo Themes Help? No 'Theme Store'

Hi, Just got my 1st Oppo & I can't find how to download new themes. I've looked everywhere on the phone. Can anyone help? Bought in UK. I've looked online and seen that there's supposed to be a 'Theme Store', that's not on my phone.

Looked at the Oppo help section on the site and it's no help as I don't even have the store. My phone is ColorOs v6.1 right now.

Don't know what to do.

Anyone else had the same issue?

Thanks