how can i lock a 3rd party application individually with touch Id?

You can't.

iPhone is not a multiuser device. You can lock the whole iPhone with a passcode.

If you want your child to use a certain app, use Guilded Access

Read here: Use Guided Access with iPhone, iPad, and iPod touch - Apple Support

Use Restrictions on your iPhone, iPad, and iPod touch = About Restrictions (parental controls) on iPhone, iPad, and iPod touch - https://support.apple.com/HT201304