html
 

<ion-item>
    <ion-label fixed>姓名</ion-label>
    <ion-input type="text" placeholder="请输入姓名" formControlName="Name" text-left></ion-input>
</ion-item>
<ion-item>
    <ion-label fixed>手机</ion-label>
    <ion-input type="tel" placeholder="请输入手机号" formControlName="Mobile" text-left></ion-input>
</ion-item>
<ion-item>
    <ion-label fixed>验证码</ion-label>
    <ion-input type="text" placeholder="" formControlName="AuthCode"></ion-input>
    <button item-right ion-button clear color="danger" [disabled]="isDisabledAuthCode" (click)="getAuthCode()">{{btnGetAutoCode}}</button>
</ion-item>
<ion-item required>
    <ion-label fixed>性别</ion-label>
    <ion-select formControlName="Sex" placeholder="请选择性别" okText="确定" cancelText="取消" text-left>
        <ion-option value="男">男</ion-option>
        <ion-option value="女">女</ion-option>
    </ion-select>
</ion-item>
<ion-item>
    <ion-label fixed>生日</ion-label>
    <ion-datetime formControlName="Birthday" displayFormat="YYYY-MM-DD" cancelText="取消" doneText="确定" interface="popover" text-left></ion-datetime>
</ion-item>

scss
 

.item {
    .select-md, .datetime-md {
        padding-left: 8px;
    }
}

.item.item-select {
    .input-wrapper {
        ion-select {
            width: 100vw;
            max-width: unset;

            /*  
            .select-text {
                text-align: start;
            }
           */  
        }
    }
}

效果图：