When you look at any profile you will see a "DNA Connections" panel to the right. If any Wikitreers who are related to this person (how closely depends on what kind of test) have entered DNA test information, that will show up there. Wikitree doesn't store any actual DNA data so you will have to use a third party site like Gedmatch to do any actual comparisons. Here's a link to the Help page: Help:DNA Test Connections (wikitree.com)