By default Vapor uses AWS API Gateway version 1 that has a 30 seconds timeout for any request. Then you have Gateway version 2 that has the same timeout but is faster in processing. The 30 seconds are defined by AWS as part of the product characteristics.
And finally you have ALB (Application Load Balancer) that has up to 4.000 seconds. There's also a catch related to maximum body size.
API Gateway v1
timeout 30 seconds
maximum body size 6 mb
API Gateway v2 (faster than v1)
timeout 30 seconds
maximum body size 6 mb
ALB
timeout 4000 seconds
maximum body size 1 mb
All of this limitations are characteristics of AWS products, to my knowledge they are not related with Vapor.
Finally these articles should help you make a decision: