Unfortunately Instagram doesn't allow you to set up a child search or child feed, but you can significantly reduce the amount of content with offensive or obnoxious content.
What do you need to do to do this?
1. Go to your child's instagram account
2. Go to the settings section.
3. Click - Filter out potentially inappropriate content
4. Click Limit more content
5. In the pop-up window, tap ok
We also recommend using the Restrictions feature additionally, this feature allows you to restrict unwanted communication if you are harassed, you can temporarily restrict unwanted comments and messages. Instagram will recommend you groups of accounts whose comments and messages you might want to restrict. Restricted comments and posts will also be hidden.
To enable this feature, you need to:
1. Go to your child's Instagram account
2. Go to settings
3. Go to Restrictions
4. Click Continue
5. Select the sections you want
6. Click Enable
Taken together, this will help reduce the risk of your child encountering unpleasant content as well as being harassed.