A direct 'Next Runt time' property will no be available but you can use the ADF trigger Rest API and analyze trigger definitions and look for recurrence property(shown below in yellow) to get the schedule and based on current date calculate the next run.

For more details abut schedule trigger definition, please check this link Schedule Trigger Definition

Also you can use the different methods explained in this link to get the details of trigger run. below is a sample azpowershell command to get the trigger run details. once you get the pattern based on that you can create some logic to calculate the next run

Get-AzDataFactoryV2TriggerRun -ResourceGroupName $ResourceGroupName -DataFactoryName $DataFactoryName -TriggerName "MyTrigger" -TriggerRunStartedAfter "2017-12-08T00:00:00" -TriggerRunStartedBefore "2017-12-08T01:00:00"

Also you can use azure monitor logs to check history run and understand the run pattern and calculate the approx next run.