Here is Koji's question translated:
Spreadsheet for iOS It is impossible to create a new template from another template with another application.
How to create files faster with G Suite templates - TechRepublic
Previously it looks like the top picture of the Web, I feel like there was a create button from the template on the + mark, but I can not find it now.
In addition, you can use custom templates without problems from PC's web, and custom templates are turned on in administrator settings.
Do you know if you need any additional settings to use on iOS?
What I use is the free version of g - suite.
確かに手持ちの iOS でも出来ませんね。