It depends on whether the organizer of the scientific conference has planned the issuance of certificates, to whom they are issued, ie or only for the speakers presenting papers at the conference, etc. Traditionally issued certificates are printed. But due to the progressive digitization and internetization of various aspects of science, it happens that certificates can also be issued electronically. The electronic form can be posted on social media and other portals, including scientific portals such as the Research Gate portal. As for some conference participants obtaining a certificate is important, the organizers of some conferences, who want to attract potential participants to a specific conference, offer issuing certificates of participation in the conference.
Usually if you participate as a speaker and/or in oral presentation, you receive a certificate. Sometimes, they also provide a certificate of attendance for just registering and attending the conference or even part of it (for example, few sessions).