是的，可以通过设置"isRequired"属性来强制用户在输入文本字段中输入内容。以下是使用C#和Bot Framework的代码示例：

using AdaptiveCards;
using Microsoft.Bot.Builder;
using Microsoft.Bot.Schema;
using Newtonsoft.Json;

// 创建Adaptive Card
var card = new AdaptiveCard(new AdaptiveSchemaVersion(1, 2))
{
    Body = new List()
    {
        new AdaptiveTextBlock()
        {
            Text = "请输入内容:",
            Size = AdaptiveTextSize.Large,
            Weight = AdaptiveTextWeight.Bolder
        },
        new AdaptiveTextInput()
        {
            Id = "inputField",
            IsRequired = true, // 设置为必填字段
            Placeholder = "在此输入内容"
        }
    },
    Actions = new List()
    {
        new AdaptiveSubmitAction()
        {
            Title = "提交",
            Data = new Dictionary()
            {
                { "type", "submit" }
            }
        }
    }
};

// 创建Attachment并发送给用户
var attachment = new Attachment()
{
    ContentType = AdaptiveCard.ContentType,
    Content = JsonConvert.DeserializeObject(card.ToJson())
};

var reply = MessageFactory.Attachment(attachment);
await turnContext.SendActivityAsync(reply);

在上面的代码示例中，我们创建了一个Adaptive Card，并设置了一个文本输入字段。通过将"isRequired"属性设置为true，我们强制用户在提交之前必须在文本字段中输入内容。