You can definitely run SSIS packages via by using Azure SQL Managed Instance Agent as explained on this article. You can run SSIS packages that are stored in SSISDB in a SQL Managed Instance, a file system like Azure Files, or an Azure-SSIS integration runtime package store by using Azure SQL Managed Instance Agent (that is equivalent to SQL Server Agent on SQL Server).
Run SSIS package in SQL MI via Agent, not ADF IR
Do you still need ADF IR to run SSIS packages in SQL MI? or you can just schedule it via SQL Agent? Looking at below link, it does not look like you still need it. I know previously, you need ADF IR but just double checking since Azure keeps on adding features every now and then.