From what I can gather, you are trying to create a system of internal links in a Google Doc. There are two effective ways to accomplish this.
One, take advantage of different headings from
Format > Paragraph styles. You can modify the look and feel of these headings as you see fit. Then, when you highlight text to create a link, you will have the option of linking to the different headings you have created.
Two, create bookmarks within your document using
Insert > Bookmark. This would be more suited to links that aren't headings but might be the start of a paragraph of something smaller that does not merit a heading. You can then create the link as with the previous option.
The design choice between the two is yours; you can mix and match them as well.