How to apply specific plugins to affect all sites (Multisite Network)

You can create a folder /wp-content/mu-plugins/ and put the plugins there.

Must-use plugins (a.k.a. mu-plugins) are plugins installed in a
special directory inside the content folder and which are
automatically enabled on all sites in the installation. Must-use
plugins do not show in the default list of plugins on the Plugins page
of wp-admin – although they do appear in a special Must-Use section –
and cannot be disabled except by removing the plugin file from the
must-use directory, which is found in wp-content/mu-plugins by
default.
WordPress Codex

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