Assuming you are talking about the configure() method, the answer is no. Consider:

$widget->configure(option => 'value');
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It's $widget invoking the configure() method. Without $widget, Tk wouldn't know what to configure.

"And can I get the input, lets say from the fith Entry-widget?"

Not using the code you have there. You'd need to store them in an array then access $entry_widgets[4].