To insert QR code,

1. Click More > Insert tab > QR Code.
2. In the Insert QR Code pop-up, choose the type of QR code and click Insert.

Insert Bar Code

To insert Bar Code,

1. Click More > Insert tab > Barcode.
2. In the Insert Bar Code pop- up, choose a Bar code format from the drop-down.
3. Enter the data to be bar coded and click Insert to insert the bar code in your document.

Editing options

The Bar code and QR code will be inserted as an image. You can click on the inserted image and edit the color, background, size, add image border, and so on.

To edit the Bar code or QR code image,

1. Click on the inserted Bar code/ QR code and click on the Settings icon to open the advanced editing options tab.
2. In the "Bar code/QR code options" tab, edit the image size, add color, border, change style and arrange the image based on your needs.

Click here for more information on how to edit images in Writer.