While patrolling pillagers and vindicators that join a patrol will have a unique behaviour where they watch the player from afar and wait for him to do the first move (at this point the player can either attack or approach to provoke or run away to avoid combat entirely and the pillagers will simply go back to patrolling), witches, illusioners and ravagers will skip this part. Despite gaining the extended view range of the patrol, instead of watching the player they will do the following:

evokers will cast spells and spawn vexes
 illusioners cast blindness and start shooting arrows
 ravagers and witches will split from the patrol to attack
 vindicators and pillagers stay back and watch the player

How to reproduce in survival:

1. Find a naturally generated patrol
2. Have a witch that spawned at night, an evoker from a mansion or a ravager left over from a failed raid join it
3. Reproduce behaviour

Reproducing in survival is unlikely (but possible) so here are the steps to reproducing in creative:

1. Spawn the mobs with spawn eggs or /summon
2. Make them patrolling with /execute as @e run data merge entity @s {Patrolling:1b}
3. (optional) consider making one of them captain with /data modify entity <insert entity UUID here> PatrolLeader set value 1b. Consider giving them a PatrolTarget too.
4. Either set to survival or spawn a villager (afar) to trigger the patrol behaviour
5. You can now reproduce the behaviour

In the attached screenshot you can see the behaviour in action: pillagers and vindicators spot the player but are not provoked (they wait for first move), while evokers, illusioners and witches attack 

Update - added ravager to testing, see screenshot.