You device is encrypted, but PIN is used for unlocking master key.
I set up a password, and select to require password at boot. I then set up a PIN for unlocking the screen, but did not select to require PIN at boot.
we can assume that you wanted different lock screen && encryption passwords.
Because you are using LineageOS, acquiring root for ADB is not issue.
For achieving what you presumably intended 1st define lock screen password or PIN - select Require password/PIN to start device. Lock device && do a power cycle - not every1 will agree with this procedure, but I tend to verify.
After successful bootstrap, for different encryption password you should either change password via ADB or terminal or purpose built application -
SnooperStopper or Cryptfs password manager
If you preffer ADB or terminal, while in shell, issue
adb root && sleep 2 && adb shell "vdc cryptfs changepw password [curent PIN/password] [new password]"
and hit return; if terminal is only option for you, issue only
vdc cryptfs changepw password [curent PIN/password] [new password]
You should always verify PW with
vdc cryptfs verifypw [PIN/password]
/data. If it does ask, or if it has problems while trying to mount
/data, then encryption is working just fine.