Yes, you can usually rely on specificity within CSS. If you’re unfamiliar with CSS it boils down to: If you have a bunch of styles targeting the same element, the more specific style will win.
<div class="custom-container"
<a class="custom-link">link here</a>
</div>
So what you’ll want to look for is whether or not the element (or a parent element) in the component you’re trying to change has a unique class somewhere… something like:
From the example above either .custom-link or if there’s no direct class on the element, utilizing the parent like .custom-container a. If the component has the style originally defined as .custom-link you can ensure it’s overridden by more specifically targeting a.custom-link.
If there isn’t a unique class somewhere in the component, you should also be able to use the plugin outlet container. When a plugin outlet is used in a customization there’s a custom class added to the container. Using the example of styling a link again, that might look something like .above-site-header-outlet.brand-header a where “brand-header” is the name of the template added from the component.
Worst case, you can also ask the person that created the component to add a class if you can’t find an easy way to style what you need.
If this is hard to follow giving a specific example from the component you’re trying to style would help.