You can back up contacts from the phone's memory via the import/export option in the contacts app's settings (creates a vcard file, .vcf, which you can then copy to another device for safety). You'll probably have to import the SIM contacts to the phone's storeage before you can do this - this may depend on what Android version your phone is running, but certainly that's the case on my phone.
Storing contacts on the SIM is very much a legacy format these days, to the extent that my current phone doesn't even allow me to add contacts to it (and my phone is > 3 years old, and never supported this). So my advice would be to move to another way of managing contacts: either sync with Google if you are comfortable with that, or move to phone storage and manage your own backups if not (and avoid Pixel phones, as they don't even allow you to add contacts that aren't associated with some account or other, or at least not using the default contacts app).
