That is defined in Matomo config. You can simply overwrite that in your config. But keep in mind, that this will also affect the UI, so if you set it to a very high number, the visitor profile might load forever:

https://github.com/matomo-org/matomo/blob/3.x-dev/config/global.ini.php#L495

Could I set visitor_log_maximum_actions_per_visit at a smaller number when using web UI, but override with a larger number when using API to query?

No. Both is currently using the same config value. Might be worth at some point to change that. Would be better if API would allow to overwrite it

Hope that an overwrite feature could be add to do this.

We're likely not going to develop this, but in case you know a wee bit of PHP, you could write your own plugin that does this.

You could create a config/config.php file containing code like this:

return array(
    'Piwik\Config' => DI\decorate(function ($previous) {
       if (!empty($_GET['module']) && $_GET['module'] === 'API') {
          $general = $previous->General;
         $general['visitor_log_maximum_actions_per_visit'] = 10000000;
         $previous->General = $general;
      }
        return $previous;
    }),
);