Can we customize the styles of the npm packages after installing in our React project according to our needs, like changing colors, etc.?

I’ve installed a npm package which is rc-slider in my React project. Now I want to customise those sliders like colors and size according to my project needs. first I inspect those element and found their selectors classname after that in node modules directory there is rc-slider/assets/index.css. I tried changing the color and size of sliders but still changes are not reflecting in web page.