I'm not sure what they call it, but you can add these packs and use them by typing a colon. In Amethyst. Not sure about other clients.
Discussion
nostr:nprofile1qqs27tmg9agj3xv993n9flcxt2jqtfqazh3trjmvj9e3yds9w38sdespr3mhxue69uhkummnw3ezucnfw33k76twv4ezuum0vd5kzmqpz4mhxue69uhk2er9dchxummnw3ezumrpdejqzyrhwden5te0dehhxarj9ekxzmny3vs5at here is Vitor's tutorial on how to do it in amethyst