How do you find your users LinkedIn/social profiles? (I will not promote)

Hi startups folks! Every time I get an email about having a new user I'm trying to find their LinkedIn profiles, sometimes it's easy (ex. mark.zuckerberg\[dot\]meta.com sometimes not (cdscs@gmail\[dot\]com). I'm sure I'm not the only one who do it, so do you do it manually or you use some tool? Thanks in advance! (I will not promote)