We can use SingleEmailMessage to send email notification from Salesforce Triggers.

The following sample trigger will send an email when the Case status is set to Escalated.

Sample Trigger:

trigger CaseTrigger on Case ( after update ) {

    List<Messaging.SingleEmailMessage> listMessages = new List<Messaging.SingleEmailMessage>(); 

    for ( Case objCase : trigger.new ) {
    
        if ( 
            objCase.Status == 'Escalated' &&
            objCase.Status != trigger.oldMap.get( objCase.Id ).Status
        ) {
    
            Messaging.SingleEmailMessage message = new Messaging.SingleEmailMessage(); 
            List<String> listToAddresses = new List < String > { 'Your Email Address' };
            message.setToAddresses( listToAddresses );  
            message.setSubject( 'Case Escalation' );   
            message.setUseSignature(false);   
            message.setHtmlBody( 
                'Case ' + objCase.CaseNumber + ' is escalated'
            );  
            listMessages.add(message);  
        
        }
    
    }
    
    if(listMessages.size() > 0) {
    
        Messaging.sendEmail(listMessages);
        
    }

}