How to change the default Send/Receive mail sync time interval in Outlook 2016

Step 1: Click the Send/Receive Groups > Define Send/Receive Groups on the Send / Receive tab.
Step 2: In the Send/Receive Groups dialog box,
Step 3: Click to highlight the send/receive group that you will change its automatic send/receive interval in the group list.
Step 4: Make sure the option of Schedule an automatic send/receive every x minutes is checked, and enter your required send/receive interval time in the box in this option.
Step 5: It’s optional to check the option of Schedule an automatic send/receive for outlook offilne mode
Step 6: Click the Close button to exit this dialog box.