Hi Min,
Thank you for querying in this forum.
From your description, it seems that you want to share a folder with external user, and you don’t want to let them download it. So you want to set Restricted permission for them, however, you cannot find such permission in your new SharePoint site.
May I know if my understanding is right? If so, we’d give you the suggestion below to create a new permission level to check if it will help you:
You can go to Settings and click Site permissions and select Advanced permissions settings > Select Permission Levels and click Add a Permission Level > Key in the name of permission level and tick the following permissions which only allow user to view pages, list items and documents but not download. As shown below:
After creating new permission level, you can assign this permission to external users, and per our test, they can access the site contents but cannot download items. As shown below:
At the same time, for new SharePoint site, Restricted view permission will not appear, Restricted view is not a built-in permission level. It shall be a custom one and being deleted by another user in that site. So we’d still suggest you use the suggestion we provided above to create a new permission level, this is the best way to achieve your requirement.
If the scenario above is not consistent with yours, you can also post back and point that.
Your understanding and patience will be highly appreciated. I hope that you are keeping safe and well!
Best Regards,
Sukie