The color of the line numbers in a word file by default is black. However, you can customize them with your preferences such as the font, the font size, and the font color. Please see below for details:
Step 1: After adding the line numbers in the word document (please check how to add the line numbers), click the "Home" tab from the ribbon;
Step 2: Click the right-bottom corner in the "Styles" area;
Step 3: In the "Styles" window, click the "Options" button at the bottom;
Step 4: In the new dialog box, select "All styles" in the first box and select "Alphabetical" in the second box;
Step 5: Move down to find the "Line number" from the list, and click the triangle right after;
Step 6: Click "Modify" from the drop-down list;
Step 7: In the "Modify Style" window, select the format you want (e.g., red);
Step 8: Click "OK" to finish.
