I am saving the Firebase server timestamp using serverTimestamp() in version 9. And then I need to do some maths, for example adding 3000ms. However it seems that serverTimestamp() reurns an object and therfore simply adding 3000 is impossible. So far I have dealt with this saving the timestamp in my database and then reading it. This way it works but it involves an extra read and write operation in the database just to get this value on JS.
Is there a way to transform the serverTimestamp object to a number directly on JS without involving writing and reading from the database?

code not working (cannot sum 3000 to an object):

var NewserverTime = serverTimestamp() + 3000;

Code working but the extra step of reading and writing in the databese seems not very elegant...

 set(ref(db, "/dabasepath"), {
    ServerTime: serverTimestamp()   
});

const firebaseRef = ref(db, "/databasepath");
onValue(firebaseRef, (snapshot) => {
          NewServerTime = snapshot.val() + 3000;  
 });