I can see that nobody has reacted yet to your question. So, as far as I know, there is no possibility to trigger an MFA warning other than signing in under that user account with an MFA method configured.
Apart from that, I recommend you check if the application supports using Service Principal instead of using Service Accounts/Non-personal accounts. Using a Service Account is an enormous risk. The account can be used for interactive login (Azure portal, for example), and a Service Account uses a username and password. I would inform the application supplier if they support Service Principals.