Hi Etienne,
Thanks for the query and we are here to assist you on this.
You can use Save List as Template. Here are the steps:
Reference: Manage list templates
First please make sure admin has turned on custom script on your tenant (Turn scripting capabilities on or off).
Then, you can
1.Go into your list’s settings page and click on “Save list as Template”.
2.Check the “Include Content” option.
3.Go to Site Contents page and click New> App> Find the list template we just create and create a new list based on it.
If by "I can't save has template has it say for other version of sharepoints", you mean there is no Save List as Template option even after turn-on of custom script, then did you turn on publishing feature as in this article?
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If yes, you can create a new list, then go to Site settings > Content and structure logs under Site Administration > navigate to the list you would like to duplicate > select all items > click Actions > Copy to copy to the new list you just created.
Regards,
Tina