I want to use transition effects in react app. What type/ library for animation in react app should I use according to the latest trend?

If you want to use a library, I would suggest react-spring https://react-spring.io/ it is based on spring physics, If you want to read about that more check this out https://www.joshwcomeau.com/animation/a-friendly-introduction-to-spring-physics/ And there is also another good option which is framer motion https://www.framer.com/motion/ which apparently offers more possibilities maybe out of the box (I personally have never tried it before) For examples you can check their websites they have good examples.