Anti-spam filtering differences in different versions of Exchange
There are extremely few differences in the anti-spam filtering features in Exchange 2013, 2016 and 2019. In general, the significant changes in the newer versions of Exchange are in other functionality areas.
The built-in anti-spam agents are the same in Exchange 2013, 2016 and 2019.
All of the settings configurable in QSS Exchange Anti-Spam Toolkit are available in all versions of Exchange.
There are also some minor user-interfaces changes in relation to the per-mailbox anti-spam settings which are configurable by users in Outlook Web App (OWA) between Exchange 2013 and 2016. There are almost no differences between OWA in Exchange 2016 and 2019. In general, Outlook Web App in all of the above versions of Exchange is very similar. Exchange on-premises does not used the same OWA interface as Exchange Online or Office 365, which has significant changes to OWA which are not available even in Exchange 2019.
There are some minor differences or additional configuration settings which are indirectly relevant to anti-spam filtering (such as additional configuration options on Receive Connectors).
Nevertheless, we recommend using the latest version of Exchange due to other functional improvements and supportability reasons, including availability of security updates.
See Antispam and antimalware protection in Exchange Server for more information.