I understand that you're addressing the warning message about updating the buffer size parameter for code generation. This warning usually indicates that the number of data points needed to store the delayed signal during simulation exceeded the buffer size specified for the Transport Delay block. To resolve this, you can open the block parameters for the Transport Delay block and increase the 'Initial buffer size' parameter to a larger value. This should address the issue.
You can refer to the following documentation to know more about how buffers work in the transport delay block - https://www.mathworks.com/help/releases/R2020a/simulink/slref/transportdelay.html?searchHighlight=transport%20delay&s_tid=doc_srchtitle#br3niji-1
Hope this helps!