Your child’s safety is always the priority. As a parent if you feel it is necessary to take their device away from them it is down to you and should be in response to a high-risk situation. You may have to grapple the phone off your child and that is not a good experience for either of you. This should be a “last resort” situation. It is demeaning for the child and undermines trust. It is better to lock the device using a Device Management app, rather than physically take the device if that is possible.
Removing the device will definitely take them off the grid in their on-line world but you will still need to seek advice for whatever the problem is. By simply returning the device at a later date – nothing has changed and they will return to the same risks. The difference is that you will have removed them from their social group and they will have missed out on everything their friends have been discussing and arranging. Also bear in mind that next time your child may not confide in you if they have an issue for fear that you will confiscate the device again.