@Michèle Merlo, Thanks for posting in Q&A.
From your description, I know you want to set specific account lockout duration setting.
Based on the official document, the AccountLockoutPolicy setting is only available for Device, therefore, when you create a custom policy, and configure all settings, you should assign the policy to device group, then the device will apply the policy and also every user login on to this device will also be affected by this policy. Therefore, currently, there is no such way to set the specific account lockout duration setting. And it is suggested that you create the policy and assign it to device group and make it to apply all users.
Thanks for your kind understanding.
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