Yes you are right 'Tag36h9' cannot be used in readAprilTag function but alt. u can use detectAprilTag function as follows:
% Load the image
image = imread('path_to_image.jpg');
% Convert the image to grayscale
grayImage = rgb2gray(image);
% Define the AprilTag detector parameters
tagFamily = 'Tag36h9';
detectorParams = aprilTagDetectorParameters('TagFamily', tagFamily);
% Detect and decode AprilTags in the image
[tagIds, tagPoses] = detectAprilTag(detectorParams, grayImage);
% Display the detected tags
imshow(image);
for i = 1:numel(tagIds)
text(tagPoses(i).Centroid(1), tagPoses(i).Centroid(2), num2str(tagIds(i)), 'Color', 'r');
end
