Yes, you can override the CSS using their parent class.
Also, use important for overrides CSS but it’s not a proper way. always first try to override CSS by using their parent class if not possible that then you can use it important.

Please review the following example of CSS override:

.owl-carousel .owl-nav button.owl-next,
.owl-carousel .owl-nav button.owl-prev,
.owl-carousel button.owl-dot {
background: 0 0;
color: #000;
border: none;
}

Body .owl-carousel .owl-nav button.owl-next,
Body .owl-carousel .owl-nav button.owl-prev,
Body .owl-carousel button.owl-dot {
color: #f00;
}

Here, you can see that override the CSS with their parent element or class.