Here are the steps I followed using a trigger but its not happening. Please help. Maybe I am missing something

1. I created a new field of Checkbox type on Contact Object to Flag contact as Key Contact
Field Name : Key_Contact__c
type : Checkbox
Object : Contact


2. The Trigger Class to Link Contacts That Flagged as key Contact when creating an Opportunity.


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trigger LinkContacts on Opportunity (before insert, before update) {
   
set<Id> AccountIds = new set<Id>();
for (Opportunity  o: trigger.new) {
 AccountIds.add(o.AccountId);
}
map<Id, Account> AccountContactMap = new map<Id, Account>();
map<Id, Contact> ContactMap = new map<Id, Contact>();
list<Account> AccConts = new list<Account>();
AccConts = [Select Id, Name, (Select Id, Name, Key_Contact__c from Contacts Where Key_Contact__c = true) from Account where Id IN : AccountIds];
for(Account acc : AccConts){
    AccountContactMap.put(acc.Id, acc);
}

for (Opportunity  o: trigger.new) {
Account Acc = AccountContactMap.get(o.AccountId);
if(Acc != null){
List<Contact> conts = new list<Contact>(Acc.Contacts);
                 map<Id, Contact> ContactMap = new map<Id, Contact>();
                  Contact Con = ContactMap.get(o.ContactId);
if(conts.size() > 0 ){
                   
                    if(Con.Key_Contact__c = true){
                       
                        for(Contact contactFlag : conts){
    ContactMap.put(contactFlag.Id,con );
}
                    }

}
}


}
}

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