While many people consider spell check as an essential feature in a web browser, Microsoft did not to ship it in the early Chromium-based Edge builds. The much-awaited spell check feature is now finally available on the latest Edge Canary build v18.104.22.168. Once this feature is enabled in the Settings menu, you can get spelling suggestions when you right click the words.
Note: Even after updating to the latest Edge Canary build, some people have spell check feature grayed out. So, it might take some time until Microsoft decides to activate this feature for everyone.