BizTalk provides mechanism to create schema from wizard. If you have sample files in xml, json, flat, or csv, then BizTalk has its own wizard to create the schema easy and fast. If you don’t have then you can create manually.
If you have xml file and want to create schema based on xml file. Then right click on project->Add-> Add Generated Items
Select Generate Schemas
Select Well-Formed XML and select xml file in Input file as above window.It will create schema. When you work on first time, it asks to install below vbs file before creating the schema.
C:\Program Files (x86)\Microsoft BizTalk Server 2016\SDK\Utilities\Schema Generator\InstallWFX.vbs
Open command prompt and run following command
cscript “C:\Program Files (x86)\Microsoft BizTalk Server 2016\SDK\Utilities\Schema Generator\InstallWFX.vbs”