On the ‘My Feeds’ section, click on the 3 dots of the feed you want to pin. Click on the ‘Pin to profile page’ on the option. 

Pinned posts will appear at the top of the model profile page and have the pin icon.

On the model landing/profile page, click on the 3 dots of the feed you want to unpin and click on the unpinned option.

The post will be removed from the top of the model profile page.