Using npm install npm install all the packages in the package.json. But it looks like you need to specify each package when using yarn add according to https://yarnpkg.com/en/docs/cli/add.
yarn add package-name installs the “latest” version of the package.
This can't be correct, can it?
Just add spaces between packages.
e.g.:
yarn add redux react-redux redux-starter-kit
If you want a replacement for npm install you can use the yarn or yarn install command.