You can put a Frame into the style that you want to have that spacing.
Some time ago, Microsoft changed Word so that the space-before is ignored at the beginning of any page except the first page in a section. This is true no matter how the page is begun, except with a Section break. It is not advisable to use a Section break just to handle this spacing. When a Frame is used, the Frame starts at the top of the page but the space before takes place inside the Frame. Frames can be invisible.
Here is my page with directions on how to create a Frame as part of a style.
Using Frames to Provide Space Before a Heading after a Page Break
In recent versions of Word, Frames are required to provide space before the heading starting a new chapter after a page break or a
column break. (Note: this is a problem with a page break or a column
break, but not a page break inserted as part of a Section break.)
By design, Word ignores the space setting for the paragraph without the Frame. The same thing happens with a column break. Word
ignores the Space-before formatting of a paragraph style (or just
paragraph formatting) when the paragraph is the first one on a page
following a page break (or at the top of a column following a column
break). You can use a Frame to get around this. The simplest method is
to modify the Style:
You would want a borderless frame and to have the space-before paragraph formatting that you need.
Excerpt from my page on Frames and Textboxes in Microsoft Word
By the way, your sample had no space-before set. Here is your document back with Heading 1 style being used and a Frame. Here is a temporary link and screenshot. The Frame shows up when text within it is selected. It does not print and does not appear when you are working outside the Frame.
You can add Page-Break-Before paragraph formatting to the style, also, if you want. This eliminates the need for the manual page break and makes editing easier. Applying the (heading) style automatically starts a new page.
Here is my writing on the importance of Styles in Word. Here is Shauna Kelly's page on how using the built-in heading styles can make things easier.
This answer applies to all versions of Word, although using Frames for this purpose is not necessary in the menu versions (Word 2003 and earlier).