To generate a package of the entire Salesforce org you can use the link below
Use https://packagebuilder.herokuapp.com/
Package.xml example (autogenerated)
<?xml version="1.0" encoding="UTF-8"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
<types>
<members>Forzatura__c.LAST_N_DAYS__c</members>
<name>CustomField</name>
</types>
<types>
<name>CustomMetadata</name>
</types>
<types>
<members>Forzatura__c</members>
<name>CustomObject</name>
</types>
<types>
<members>Forzatura__c-it</members>
<name>CustomObjectTranslation</name>
</types>
<version>49.0</version>
</Package>
After generate package.xml you retrive all metadata
Example minimal and puntual package.xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
<types>
<members>SignatureMethodSection</members>
<name>AuraDefinitionBundle</name>
</types>
<types>
<members>CommodityVolturaSection</members>
<members>CommodityVoltura_Test</members>
<name>ApexClass</name>
</types>
<version>51.0</version>
</Package>