Is the a way to only load plugins when necessary?

Is the a way to not autoload a plugin, but have some macro or script to load it when desired?

this is determined first by the plugin itself (i.e. you can specify whether your plugin must be loaded at startup or not), and then by whether it is necessary at some given point in time – for example it must be loaded to read any data it may have written into a file

I don’t know if there is any specific command for explicitly loading a plugin, but for plugins that load when necessary, calling any command they provide will cause them to load, so you could script/macro some inconsequential command (like printing version), if they have a suitable one