how to turn off screen time for one day without losing all settings

You can turn-off individual categories of ScreenTime settings without losing the associated settings.

By example...:

Settings > ScreenTime > Content & Privacy Restrictions > Content & Privacy Restrictions - set from ON to OFF.

When disabled, any associated settings for this category are unchanged - but simply not active while disabled. When the category is again re-enabled, all the settings will be reapplied.

If you have multiple categories enabled, these may need to be disabled as required. Temporary changes may not require all categories to be disabled.