If you are unfamiliar with OpenBSD's package system, please read the FAQ first.
To install a package (like nvi):
$ doas pkg_add nvi
To delete a package:
$ doas pkg_delete nvi
To delete unused dependencies:
$ doas pkg_delete -a
To find a package from repositories:
$ doas pkg_info -Q nvi
To learn more about a package:
$ doas pkg_info nvi
On occasion, you may encounter errors:
$ doas pkg_add package https://cdn.openbsd.org/pub/OpenBSD/7.1/packages-stable/amd64/: ftp: cdn.openbsd.org: no address associated with name https://cdn.openbsd.org/pub/OpenBSD/7.1/packages/amd64/: ftp: cdn.openbsd.org: no address associated with name https://cdn.openbsd.org/pub/OpenBSD/7.1/packages/amd64/: empty Can't find package
To change the mirror, edit
/etc/installurl to use a different mirror from the list of OpenBSD mirrors.
If the issue is your local nameservers, you may want to configure unbound.