By default, Magento limits the number of options that can be displayed in a drop-down menu to 20 per page to improve performance. However, you can change this limit by modifying the "Maximal Values to Show in Dropdowns" setting in the Magento Admin Panel.
To do this, follow these steps:
- Login to your Magento Admin Panel.
- Go to Stores > Configuration.
- In the left-hand menu, click on "Catalog" and then select "Product Options".
- Under the "Configurable Product Options" section, find the "Maximal Values to Show in Dropdowns" setting and enter the maximum number of options you want to display in the drop-down menu.
- Click "Save Config" to save your changes.
After making this change, you should be able to display more than 20 options per page in your drop-down menus.