w3schools mentions here that there are only 6 children elements allowed for the Head element. I couldn't find verification on w3.org, but they are usually right. The six elements mentioned by w3schools are:
<base>, <link>, <meta>, <title>, <style>, and <script>
The title element is the only one that is required.
I usually just use title, meta and link.
Below are links for 9 different methods to insert three children (<title>, <meta> and <link>) for the <head> parent element.
innerHTML, all 3 children at once
innerHTML, Child1, Child 2, Child3
innerHTML, Child3, Child2, Child1
innerHTML, Child1, Child3, Child2 using innerHTML
innerHTML, Child1, Child2, Child3 using outerHTML
insertAdjacentHTML "beforeBegin, strHTML
insertAdjacentHTML "afterBegin, strHTML
insertAdjacentHTML "beforeEnd, strHTML
insertAdjacentHTML "afterEnd, strHTML
