see react version code example

Example 1: check react version

npm view react version
npm view react-script version

Example 2: get react version

// To view which version of React is/was used for a particular app, type in the below in commandline/terminal.
npm view react version
npm view react-native version

Example 3: create-react-app version check

{
  ...
  ...
  ...
  "name": "react-app",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@testing-library/jest-dom": "^4.2.4",
    "@testing-library/react": "^9.5.0",
    "@testing-library/user-event": "^7.2.1",
    "react": "^16.13.1",
    "react-dom": "^16.13.1",
    "react-scripts": "3.4.1"
  },
  ...
  ...
  ...
}