To Avoid putting any time limits for an app(s) like Phone, SMS, etc, please try this approach:
1. Make Sure you have not set any daily time limit and blocked time slots at device level (At Kids Place level) in time schedule screen. To check this, go to configure time schedule > apps tap > device and clear all time slots and make sure daily time limit is set to 23:59 fro all days of week. This will make sure screen time control won’t be applied at Kids Place or device level.
2. Create a new category (or use an existing) and assign the apps like phone, sms, etc to this category. Make sure this new category also do not have any time limits.
3. You can than apply screen time limits for other categories and app level.