Displaying system messages without pressing a button?

Question

Joomla

Hello! Explain to a Joomla lover how to display system messages.
My template allows you to display this type of message

in the upper right corner of the screen... They are displayed when you click on the view button...

<button id="default-primary" class="mt-sm mb-sm btn btn-primary">Primary</button>
<button id="default-notice" class="mt-sm mb-sm btn btn-warning">Warning</button>
<button id="default-success" class="mt-sm mb-sm btn btn-success">Success</button>
<button id="default-info" class="mt-sm mb-sm btn btn-info">Info</button>
<button id="default-error" class="mt-sm mb-sm btn btn-danger">Error</button>
<button id="default-dark" class="mt-sm mb-sm btn btn-dark">Dark</button>

But how can I display this at the very error so that I don’t have to press the button, but are displayed automatically like system messages ....