Display same row between checkbox and text – Flutter

You can achieve this with a inner Row Element and a Padding element around the Text like so (16.0 is a example value):

child: Container(
              decoration: BoxDecoration(
                color: Colors.white,
                borderRadius: BorderRadius.circular(25.0),
                boxShadow: [
                  BoxShadow(color: Colors.grey[500], blurRadius: 3.0, spreadRadius: 1.0),
                ],
              ),
              width: data.size.width * 0.26,
              height: data.size.width * 0.26 * 1.2,
              padding: EdgeInsets.all(data.size.width * 0.02),
              child: Column(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: [
                  Row(
                     children: [
                        Checkbox(
                           checkColor: Colors.white,
                           value: isChecked,
                           onChanged: (bool value) {
                              setState(() {
                                 isChecked = value;
                           });
                       },
                    ),
                    Padding(
                       padding: EdgeInsets.only(left: 16.0),
                       child: Text(
                          'Title Here',
                           style: TextStyle(color: Colors.black87, fontSize: data.size.width * 0.02, fontWeight: FontWeight.bold),
                        ),
                     ),
                  ]),
                  AvatarLetter(
                    size: 100,
                    backgroundColor: getBackColor(),
                    textColor: Colors.white,
                    fontSize: 40,
                    upperCase: true,
                    numberLetters: 3,
                    letterType: LetterType.Circular,
                    text: this.type,
                    backgroundColorHex: null,
                    textColorHex: null,
                  ),
                  Text(
                    this.Type ?? '',
                    textAlign: TextAlign.center,
                    style: TextStyle(color: Colors.black87, fontSize: data.size.width * 0.02, fontWeight: FontWeight.bold),
                  ),
                  Text(
                    DateFormat('dd MMMM yyyy').format(DateTime.parse(this.inspectDetails.testDate)).toString(),
                    style: TextStyle(
                      color: Colors.grey[400],
                      fontSize: data.size.width * 0.02,
                      fontWeight: FontWeight.bold,
                    ),
                  ),
                ],
              ),
            )