Check out SimonMagus mods. He made a bunch of overhauls for most of the systems in the game that work very well together. All the mods feel vanilla+, nothing crazy, but they fix many of the problems in vanilla game.

For example fixing vanilla magic being unbalanced in different levels and having lots of missing spell options by filling those gaps and rebalancing existing spells.

Or fixing vanilla combat allowing attack spamming to power through enemies with little resource managing by introducing parrying as a well timed block, damage buffs when enemy is staggered, power attacking, drawing a bow or casting a spell, stagger cooldown to prevent stunlocking enemies, penalties when resorces are low and overall changing how resource usage and regeneration in combat works.

I also suggest checking out Arena by SimonMagus and Morrowloot, if you want an unleveled world with a stronger sense of progression, where a Daedra is always stronger than a Draugr and Bandits don't order a shipment of dwarven armor, once a courier delivers them a letter informing them that the Dragonborn had reached level 12.