Individual components from a more recent theme release cannot be implemented retrospectively, as the additional functionality affects other elements of the theme's code.
The update would need to be installed in its entirety and any custom work then moved across to it by a coding specialist. For additional context, the Shopify platform allows for 20 "slots" where you can save theme installs and duplicates - these are not connected, so any changes you make to one, will not affect another.
Downloading a theme update will reside in one of these isolated slots.
This is a Shopify platform limitation rather than theme-specific (paid or free).
You will be able to work on your newly installed update in your admin area and make sure you are totally happy with it before sending it live:
We can personally recommend this app for added peace of mind when it comes to Theme installation and updates: