trigger UpdateContactOwner on lead (before update) {

    list<lead> collectleads=new list<lead>();
    list<string> LeadEmails=new list<string>();
    list<string> LeadPhones=new list<string>();
    list<contact> UpdateContacts=new list<Contact>();
 
    for (lead l : Trigger.new) {
    // Access the old veersion of record by its ID in Trigger.oldMap
    lead oldleadrecord = Trigger.oldMap.get(l.Id);

   // fetch old version record owner
    String oldleadOwner = oldleadrecord.ownerId;
    String newleadOwner = l.ownerId;
    
    // Check that if the lead owner is been updated 
    if (oldleadOwner!=newleadOwner) {
        collectleads.add(l);
        LeadEmails.add(l.email);
        LeadPhones.add(l.Phone);
    }
  }

//Collecting all contact having matcing email and phone with leads.
list<contact> contactlist=[select id,lastname,email,phone from contact where email in :LeadEmails and Phone in :LeadPhones];

    // If leads phone and email matches with contacts phone and email Updating contact owner to lead new owner.
for(lead l:collectleads){
for(contact c:contactlist){
if(l.Email==c.email && l.phone==c.phone){
c.ownerId=l.ownerId;
updatecontacts.add(c);
}
}
}
if(updatecontacts.size()>0){
Update updatecontacts;
}
}