Di seguito un esempio di package.xml da usare per recuperare i metadati dalla org di Salesforce con visual studio code

In questo esempio vengono recuperati i file di tutte le tipologie come ApexClass, Trigger, etc

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
    <types>
        <members>*</members>
        <name>ApexClass</name>
    </types>
    <types>
        <members>*</members>
        <name>ApexComponent</name>
    </types>
    <types>
        <members>*</members>
        <name>ApexPage</name>
    </types>
    <types>
        <members>*</members>
        <name>ApexTestSuite</name>
    </types>
    <types>
        <members>*</members>
        <name>ApexTrigger</name>
    </types>
    <types>
        <members>*</members>
        <name>AuraDefinitionBundle</name>
    </types>
    <types>
        <members>*</members>
        <name>StaticResource</name>
    </types>
    <version>45.0</version>
</Package>

Per recuperare solo una lista finita di file si procede in questo altro modo

<?xml version="1.0" encoding="UTF-8"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
    <types>  
        <members>nomeClasseUno</members>
        <members>nomeClasseDue</members>
        <members>nomeClasseTre</members>
        <members>nomeClasseQuattro</members>
        <name>ApexClass</name>          
    </types>      
    <version>45.0</version>
</Package>

Documentazione per il retrive dei dati