ionic 5 outline button as default code example
Example 1: ion-button outline
<ion-button expand="full" fill="outline">Outline + Full</ion-button>
Example 2: ion button outline
<ion-button color="primary" fill="outline">Primary</ion-button>
<ion-button expand="full" fill="outline">Outline + Full</ion-button>
<ion-button color="primary" fill="outline">Primary</ion-button>