​​Make the CSS:​​

.ngx-select__choices {
   width: auto !important;
}

And... Make it out of a component. Or make it with /deep/, but it is deprecated now:

// 已弃用。。但是可以用。。。

// :host /deep/.ngx-select__choices {
//   width: auto !important;
// }

:host ::ng-deep .ngx-select__choices {
  width: auto !important;
}