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 );
        
    }

}