Queueable interface can be used to attach a Salesforce Visualforce as PDF to an outgoing email from trigger.

Sample Visualforce page:

<apex:page standardController="Account">
    <apex:pageBlock >
        <apex:pageBlockSection >
            <apex:pageBlockSectionItem >Account Name</apex:pageBlockSectionItem>
            <apex:pageBlockSectionItem >{!Account.Name}</apex:pageBlockSectionItem>
            <apex:pageBlockSectionItem >Account Number</apex:pageBlockSectionItem>
            <apex:pageBlockSectionItem >{!Account.AccountNumber}</apex:pageBlockSectionItem>
            <apex:pageBlockSectionItem >Industry</apex:pageBlockSectionItem>
            <apex:pageBlockSectionItem >{!Account.Industry}</apex:pageBlockSectionItem>
        </apex:pageBlockSection>
    </apex:pageBlock>
</apex:page>

Sample Trigger:

trigger AccountTrigger on Account ( after update ) {
    
    System.enqueueJob( new EmailNotificationWithPDF( trigger.new ) ); 
    
}

Sample Queueable Interface:

public class EmailNotificationWithPDF implements Queueable, Database.AllowsCallouts {
    
    List < Account > listAccounts;
    
    public EmailNotificationWithPDF( List < Account > listAccounts ) {  
        
        this.listAccounts = listAccounts;
        
    }  
    
    public void execute( QueueableContext qc ) {  
        
        List < Messaging.SingleEmailMessage > listMessages = new List < Messaging.SingleEmailMessage >();
        
        for ( Account acc : listAccounts ) {
            
            Messaging.SingleEmailMessage objMessage = new Messaging.SingleEmailMessage();
            Messaging.EmailFileAttachment objAttachment = new Messaging.EmailFileAttachment();
            objAttachment.setContentType( 'application/pdf' );
            objAttachment.setFileName( 'Sample.pdf' );
            PageReference objPR = Page.AccountPage;
            objPR.getParameters().put( 'id', acc.Id );
            Blob emailBody = objPR.getcontentAsPdf();
            objAttachment.Body = emailBody;
            objMessage.setToAddresses( new String[] { '<Email Address>' } );
            objMessage.setSubject( 'PDF Generation' );
            objMessage.setHtmlBody( 'Please check the attachment' );
            objMessage.setFileAttachments(
                new Messaging.EmailFileAttachment[] { objAttachment } 
            ); 
            listMessages.add( objMessage ); 
            
        }
        
        Messaging.sendEmail( listMessages );
        
    }  
    
}