I’m always surprised by how few lightning themed spells there are in 5e, especially considering how prevalent it is in fiction. I wrote up a few, and buffed core lightning bolt in the hope to see these get some more play, specifically for arcane casters. There’s shocking grasp as a cantrip, witchbolt as a 1st, call lightning as a 3rd level druid spell, the classic lightning bolt, storm sphere kind of at 4th level, chain lightning at 6th, and storm of vengeance at 9th. As a wizard, you might land with shocking grasp, lightning bolt, chain lightning and storm of vengeance. Its a couple, but you don’t really get options, you’re sort of left with a binary yes/no do I want to be a lightning guy, and if so, you take them all.
Here’s some additional spells, and a little tweak to an old classic (with a rant).

Electric Wreath: 2nd level conjuration. Casting Time: 1 action. Range: Self. Components: V, S. Duration: Concentration, up to 1 minute. Sorcerer, Warlock, Wizard.
You are wreathed in a sphere of crackling lightning for the duration. You can end the spell early by ceasing concentration. Whenever a creature within 5ft of you hits you with a melee attack, they take 1d8 lightning damage.
Lightning Strike: 5th level evocation. Casting Time: 1 action. Range: 100ft. Components: V, S. Duration: Instantaneous. Sorcerer, Warlock, Wizard.
With arms outstretched to the sky, you summon a vertical column of lightning which strikes a point on the ground in a location you specify. Each creature in a 10-foot-radius, 40-foot-high cylinder centered on a point within range must make a Dexterity saving throw. A creature takes 8d6 lightning damage on a failed save, or half on a successful one. Creatures wearing metal armor or composed of mostly metallic materials have disadvantage on this save.
At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the damage increases by 1d6 for each slot level above 5th.
Arc Lightning: 7th level conjuration. Casting Time: 1 action. Range: Two creatures within 120ft, which are no more than 30ft apart. Components: V, S. Duration: Concentration, up to 1 minute. Sorcerer, Warlock, Wizard.
You point to two creatures and amplify the air between them causing a bolt of lightning to spark between them. Both creatures, and any creatures in a line directly between them, must make Dexterity saving throws or take 8d6 lightning damage on a failed save, and half that on a success. If either targeted creature takes any lightning damage from this spell, a current is established. So long as you maintain concentration on each of your turns, the current will arc again. When it does so, both creatures, and any between them, must make another dexterity saving throw or take 4d6 lightning damage on a failed save, and half that on a successful one. Once a current is established, the targets do not need to remain within 30ft for you to sustain it.
Lightning Bolt
When’s the last time you picked lightning bolt over fireball?
Lightning bolt has some core problems, and the biggest is that it’s hard to use. Its damage is comparable, and it hits the same amount of creatures, maybe even more, than fireball, but it just doesn’t work. Fireball lets you blast a group of dudes “over there”. Lightning bolt leads from your hands, and hits everyone in a line. It turns out that a group of dudes is way more common than a bunch of enemies in a line. Especially when you consider trying not to fireball or lightning bolt your friends. Lightning bolt comes out ahead if you’re in a hallway, and if you are on the front lines. Otherwise, fireballs probably better. I’m going to make it a little more complicated, and harder to rule with a grid, but a lot more fun with the following paragraph. Now, there’s a reason to pick it.
A lightning bolt bounces off of a solid, nonliving surface at a 90-degree angle. This doesn’t extend the distance the lightning bolt can travel, but it does allow for a creature to be struck multiple times, requiring multiple saving throws, with clever positioning.
Now theres at least some tactical draw, and the potential to do some serious damage compared to fireball. It still may be hard, maybe even harder, to use, but IMO its a fun challenge vs an awkward one.