According to this official document:
"For information about which Outlook clients are supported by Exchange 2016 and Exchange Online, see "Supported clients" in Exchange 2016 system requirements."
And from the linked article mentioned above, the supported clients for Exchange Online and Exchange 2016 are as follows:
• Outlook 2016
• Outlook 2013
• Outlook 2010 SP2 and updates KB2956191 and KB2965295
• Outlook for Mac for Office 365
In addition, from Exchange 2019, Exchange On-premises is designed not as the same as Exchange Online. So they will be a little different.