Although not technically required by WCAG, it is best practice to underline link text. Underlining links is a method to distinguish a link from regular text. If there are links on your webpage and they are not underlined, provide an underline for each link. Additionally, if color is the only way to differentiate links from regular text, ensure the link color meets a 3:1 ratio against the surrounding text.
For a deeper dive into links and link styling, explore the Landmarks, Links and Headings course from Accessible Web Academy.