Adding custom attributes to links in dynamic rich text

I always add custom attributes of rel=“noopener” to any external links on my websites to prevent this ‘links to cross-origin destinations are unsafe’ warning in Google lighthouse.

However I can’t figure out a way to apply this attribute to links in dynamic rich text coming from a CMS collection.
I know you can add custom attributes to links in static rich text like so:

Unfortunately, as soon as I get the rich text from CMS collection, there’s no way to add these attributes. It’s also not possible to add attributes when editing the rich text of your CMS, the only available settings are link type and ‘open in new tab’
With my very limited coding knowledge I also tried adding this custom code but it didn’t work:

.rich-text a{

Any help would be appreciated!

Here is my public share link: [LINK][1]
([how to access public share link][2])

Live website: