Where do you get the time from? Front matter?
If so (and you’re willing to use dictionary keys without a space), you could use the Dataview plugin like so:
---
start: 2021-04-24T14:00
end: 2021-04-24T15:30
---
### Test duration
`= this.end - this.start`
`= (this.end - this.start).minutes`
Will display:
Test duration
1 hours, 30 minutes
30
Note: Dataview as used above will not show the “total minutes” but just the minutes part of the duration.
To easily create the datetime “stamps”, you could use a Templater template and insert it.