From https://webbtelescope.org/resource-gallery/articles. (This is a slightly updated reprint of an article originally run Nov 2021.)

NASA’s James Webb Space Telescope (JWST), scheduled to launch on December 18, will primarily use its spectrographs – specialized instruments that capture and spread out light like a rainbow – to study exoplanets. By analyzing this data, known as spectra, researchers will be able to measure exoplanets’ compositions and chemistries. Spectra will help refine what we know about any exoplanet Webb observes, including massive gas giants, mid-sized ice giants, and smaller rocky exoplanets (some of which could be similar to Earth). In a few cases, JWST will deliver images of exoplanets to reveal more about them.