I mean, your entire first paragraph lists combos that are possible and effective in 5e.
-Spellcaster paralyzes enemy (e.g., Hold Person, Entangle, etc) for your Melee fighter to get Advantage on attacks (but oops you could just backstab for free Advantage anyway)
-Spellcaster casts spell on enemy to make them run away, provoking AoO (e.g., Fear, Bard's Dissonant Whispers)
-Fighter Battlemaster's Distracting Strike or Shove Prone gives an ally Advantage on an attack (but oops you could just backstab/high ground for free Advantage)
-Fighter's Pushing Attack or Shove to push an enemy into terrain created by ally (from e.g., Entangle)
-Spellcaster casts spell on enemy to decrease their Saving Throws (e.g., Bane, bestow curse), making it easier for allies to do things to enemies
and many more. Some subclasses/spells/party compositions are better for combos than others.
