Well, you have a few choices:
1) Don't do anything and live with it. If the crack didn't affect touch sensitivity or the display panel, AND IT DOESN'T CUT YOUR SKIN, then you can just live with it. Bear in mind that waterproofing is probably compromised, so exert extra caution when it comes to liquids around your device.
2) Replace the whole thing. Unfortunately most of the time you can't just replace the glass without having to replace the display panel as well, but a repair shop could probably provide further info (side note, the Note 9 does not have an LCD panel, it's an OLED one).
3) Replace the whole thing, especially if you have insurance on it. Some home-owners/renters insurance covers mobile devices as well, but check that your rate doesn't go substantially up for a 'tiny' claim.