Send Beautiful HTML emails from Bubble Through API connector

I see now, you are right, you would need to add more parameters in the Sendinblue template. For example %PARAM1%, %PARAM2% etc…
then in the API connector you need to list all these as follows
{
“to”:"justing@gmail.com",
“attr”:[{“FIRSTNAME”:“Justin”},{"PARAM1}:“something1”},{“PARAM2”}:“something2”}]
}