It is strongly recommend to create bootable rescue media immediately after the first backup; if the operating system crashes, the only way to restore it from Acronis True Image 2019 backup is restoring from the bootable media.
If your Mac includes the Apple T2 chip then you need to modify Secure Boot settings in order to boot from Acronis Bootable Rescue Media: see Acronis True Image 2019 on Mac: Changing startup options on Apple T2 chip
Follow these instructions to create a bootable media.
Connect a removable drive to your Mac
Open Acronis True Image
In the File menu, click Create Rescue Media. The Acronis Media Builder window opens
Then click Create Media
Select the drive that you want to make bootable
Click Create Media. If the drive is not empty, Acronis True Image 2019 will ask you to confirm deleting all the data stored on the drive. To confirm, click Erase
When the progress is complete, disconnect the media and keep it in a safe place. You can store your own data on the media, but make sure that you do not delete or modify the Acronis boot files.
It is recommended that you create a new rescue media every time you upgrade your Mac OS X to a newer version. Otherwise, your rescue media may not work properly.