Yes, you can use iMessage with your eSIM. 

Please keep in mind that you may need to reset iMessage after installing your eSIM. You can do so by following the steps below:

1. Go to Settings on your device

2. Go to Messages

3. Toggle iMessage OFF 

4. Toggle iMessage back to ON

5. Tap on Send & Receive

6. Uncheck your number and make sure your email address is checked. This way, you’ll be able to send and receive iMessages with only a data connection.

When you no longer have a need for your eSIM, and wish to switch back to your Primary SIM, you can do so by following these steps:
Settings > Messages > Send & Receive and check your phone number again.