can i create a child account for an iPhone without parent having iPhone or Mac?

You can create a child account for children between 13 and 18 years old just like any other account.

click here ➜ How to create a new Apple ID - Apple Support

If the child is under 13, then you do need an Apple device and Family Sharing to create an Apple ID for them.

You can create a normal Apple ID, and then apply parental restrictions directly on the child's device. The Age of the account has no direct relation to the Parental Restrictions.

click here ➜ Use parental controls on your child's iPhone, iPad, and iPod touch - Apple Support

You won't be able to enable Ask to Buy without an Apple device of your own however.

Creating a child's (presuming your child is under 13 and not a 40 year old daughter) must be done under the auspices of Family Sharing which in turn requires an Apple device for setting up.

Follow the instructions in this support article to create an Apple ID for your child - Create an Apple ID for your child - Apple Support