Apex Code

    @AuraEnabled
    public static Email_Sending__c saveFile(Map<string, string> emailRecord, String strFileName, String base64Data) 
    {
       Email_Sending__c emSend=new Email_Sending__c();
       emSend.Email__c=emailRecord.get('Email');
       emSend.Message__c=emailRecord.get('Email_Message');        
       emSend.Sent_Status__c=emailRecord.get('Email_Status');
       emSend.Subject__c=emailRecord.get('Subject'); 
       emSend.RecordId__c =  emailRecord.get('RecordId'); 
       insert emSend;
        
       base64Data = EncodingUtil.urlDecode(base64Data, 'UTF-8');
        
       if(strFileName != '' && base64Data != '')
       {
           ContentVersion cv = new ContentVersion();
           cv.Title = strFileName;
           cv.PathOnClient = '/' + strFileName;
           cv.FirstPublishLocationId =emSend.Id;
           cv.VersionData = EncodingUtil.base64Decode(base64Data);
           cv.IsMajorVersion = true;
           Insert cv;
        }
        return emSend;
   }


   JS Code
        handleFilesChange(event) {
        if(event.target.files.length > 0) {
            this.filesUploaded = event.target.files;
            this.fileName = event.target.files[0].name;
        }
        }

    uploadHelper(paramStatus) {
        if(this.filesUploaded.length > 0) 
        {
            this.file = this.filesUploaded[0];
            if (this.file.size > this.MAX_FILE_SIZE) {
                    window.console.log('File Size is to long');
                    return ;
            }

            this.fileReader= new FileReader(); 
            this.fileReader.onloadend = (() => {
                this.fileContents = this.fileReader.result;
                let base64 = 'base64,';
                this.content = this.fileContents.indexOf(base64) + base64.length;
                this.fileContents = this.fileContents.substring(this.content); 
            });
            this.fileReader.readAsDataURL(this.file);
        }
        this.contactRecord['Email'] = this.storeRecords.toString();
        this.contactRecord['Email_Message'] = this.emailMessage;
        this.contactRecord['Subject'] = this.emailSubject;
        this.contactRecord['Email_Status'] = paramStatus;
        this.contactRecord['RecordId'] = this.recordId;

        if(this.filesUploaded.length > 0) 
            this.saveToFile();
        else
            this.saveToWithoutFile();
 
    }