Hi there ??
At the moment, there’s no default option for that in WooCommerce, and setting that as the default would require quite a bit of additional coding.
However, here is a guide that could help you to achieve this. Here is the link:
https://storepro.io/learn/how-to-change-out-of-stock-text-in-woocommerce/
Please kindly note that this requires some custom coding – which goes beyond the scope of support we are able to provide in this forum.
If you do require more help with the actual coding, we’d recommend you hire a developer who can take a look at this, quote you for their services, and help you add this feature to your site. We’d recommend getting in touch with a web developer or one of the customisation experts listed at https://woocommerce.com/customizations/.
Cheers! ??