When I start my project using command expo start , Expo is starting the Metro bundler but not opening the developer tool. Also developer tool option is not available in commands menu.
I suppose there should be command option : 'd' which will launch the developer tool on the localhost:19002 but it's not coming for me.
Using expo cli version 5.4.4
If you're using a library such as react-navigation or anything (or itself) the relies on reanimated you won't be able to use remote debugging. https://docs.expo.dev/versions/latest/sdk/reanimated/
Developer tools removal
Since the release of expo-cli@6.0.0 the expo team has decided to discontinue the Web UI they had put in place. You can find more details about this in this blog post.
All of the actions that could be done within the Web UI can be done within the command line interface. For example, one used to be able to change connection mode directly within the UI : 
Now to start expo in --tunnel mode you would have to have ngrok installed on the new expo version npm i -g @expo/ngrok and to run npx expo start --tunnel. Details on the CLI can be found in the docs here.
Accessing the Developer tools anyway
If you still wish to use the developer tools web UI, there are two options :
expo-cli@5.0.2 which is linked to that sdk. However, it is not recommended to stay on older versions which will be discarded at some point.After changing the expo sdk version from 45.0.4 to 44.0.6, I am able to see the Developer tools running on http://localhost:19002.