Angular material align menu tabs in the center

You can add mat-align-tabs="center" to the nav to make it center... See below...

<mat-toolbar>
 <nav mat-tab-nav-bar mat-align-tabs="center" aria-label="weather navigation links" [backgroundColor]="tabNavBackground">
    <a mat-tab-link routerLink="/lala">lala</a>
    <a mat-tab-link routerLink="/lala2">lala2</a>
    <a mat-tab-link routerLink="/lala3">lala3</a>
 </nav>
</mat-toolbar>

You could use the CSS property flex.

Add this class e.g. in your styles.css or in the CSS file of your component:

.toolbar-flex {
  flex: 1 0.5 auto;
}

Your HTML would then look like:

<mat-toolbar>
    <span class="toolbar-flex"></span>
    <nav mat-tab-nav-bar aria-label="weather navigation links" [backgroundColor]="tabNavBackground">
        <a mat-tab-link routerLink="/lala">lala</a>
        <a mat-tab-link routerLink="/lala2">lala2</a>
        <a mat-tab-link routerLink="/lala3">lala3</a>
    </nav>
    <span class="toolbar-flex"></span>
</mat-toolbar>