I assume you refer to the WCAG 2.1 Success Criterion 1.4.1: Use of Color
It is a little more nuanced. Color alone can meet the success criterion if the contrast ratio is high enough between the background and between the surrounding text. From the page in the link above:
If content is conveyed through the use of colors that differ not only in their hue, but that also have a significant difference in lightness, then this counts as an additional visual distinction, as long as the difference in relative luminance between the colors leads to a contrast ratio of 3:1 or greater. For example, a light green and a dark red differ both by color (hue) and by lightness, so they would pass if the contrast ratio is at least 3:1. Similarly, if content is distinguished by inverting an element's foreground and background colors, this would pass (again, assuming that the foreground and background colors have a sufficient contrast).
The page links to technique G183 which describes this in a more practical way:
The hypertext links in a document are medium-light blue (#3366CC) and the regular text is black (#000000). Because the blue text is light enough, it has a contrast of 3.9:1 with the surrounding text and can be identified as being different than the surrounding text by people with all types of color blindness, including those individuals who cannot see color at all.
But as webaim.org mentions:
If you start exploring this, you’ll find that this requirement leaves only a small window of available page and link colors. For example, if your page has black text on a white background and you use the standard blue color for links, the link color must be between approximately this color of blue (#6a5eff) and this color of blue (#531fff). Any lighter or darker and it will not have sufficient contrast to the adjacent black text or to the white background, respectively.
And if your text/background colors aren’t pure black and white, this significantly narrows or eliminates the window of colors with sufficient contrast.
You will still need to account for hover and focus states making this only more difficult. So it is technically possible to meet the criterion and some companies/designers may find that sufficient, but it is still not recommended. From the page on technique G183 above:
While using this technique is sufficient to meet this success criterion, it is not the preferred technique to differentiate link text. This is because links that use the relative luminance of color alone may not be obvious to people with low vision. If there are not a large number of links in the block of text, underlines are recommended for links in blocks of text.