Searches in influData always run per platform: you choose Instagram, TikTok, YouTube or another platform at the top of the search and get results from that platform. The current search sidebar has no separate filter for "creator also has an account on platform X".
Cross-platform presence is shown on the profile instead: at the top of a creator's profile page you see a tab for every platform on which influData has linked a profile for this creator, for example Instagram, TikTok and YouTube (and, where linked, Twitch, Facebook, Snapchat or LinkedIn). One click switches to that profile with its own metrics. If a link is missing or wrong, use the small edit button next to the platform tabs to correct the linked accounts.
Keep in mind that many creators do not publish their other accounts, so a missing tab does not always mean that the creator has no account there. When you add a creator to a campaign, influData also lists the creator's connected accounts under Also on other platforms, so you can track all of them together.