Anyone on Instagram can tag, mention, request to message you, and add you to group messages unless you change this in your privacy settings. Your account may appear in search engine results but only your profile picture and bio will be visible.

If your Instagram account is set to private and you add a hashtag to your post, the post won't appear on the corresponding search results.

Make sure, your account is not set private in settings. Login to your Instagram Account. Go to 'Settings' followed by “Account Privacy” and make sure that the “Private Account” toggle is set to “off.” Use schema markup for your social profile to tell search engines which social media profiles are yours.