What kind of security/encryption is provided when setting a boot PIN on Android/Samsung

[I'm hoping this is the right sub for this question, but if not please direct me to a more appropriate one.]

I have enabled (what I think is) the passcode encryption option on my Samsung S9. So instead of just a meeting the passcode to open the main home screen, it needs it to boot: From a completely off state, when you power on the device it gives the Samsung startup animation as usual, and then the animation for my cell carrier, and then a simple menu to enter the passcode before you can continue any further. Once you do, it verifies, and then you get a little loading wheel around a padlock for about 30 - 45 seconds, and then eventually it takes you to the home screen - you do not have to enter the passcode again.

So my question is, what exactly is going on here and how secure is it.

• 1. Assuming the phone is off, does this actually provide full volume encryption for the storage and the RAM?
• 1. What if the phone is powered on, but I have just locked it, does enabling this feature provide any more security then?
• 1. If yes to 1, what is the quality of the security encryption that this provides? Is it basically similar to what Apple does with the secure enclave, and the auto white feature, or is it something less?
• 1. Is this specific encryption implementation - either on the current version of Android, or on the S9 in particular - known to have any specific vulnerabilities?