I keep looking these up, so dropping them here so I don’t have to: –
This will echo all output from a Unity project; adb logcat Unity:V *:S
This will echo all output from a Unity project to a file; adb logcat Unity:V *:S -d >> output.txt
This will clear the log; adb logcat -c
This will increase the buffer size so you have more than a few seconds before your logs start to disappear; adb logcat -G 16M