Hi Neha,
If I understand your question correctly, you want to use sendgrid's dynamic transactional template and send it with the data filled in OutSystems form.
For this you have to consume and call sendgrid API in OutSystems to send data and trigger email. I think usual way of sending email using SMTP will not work.
Here is the reference link to find the details of the sendgrid API for sending email using dynamic template
https://sendgrid.com/docs/ui/sending-email/how-to-send-an-email-with-dynamic-transactional-templates/