I play a lot of clerics and warlocks, and one thing that bothers me a lot is the lack of lighting and thunder cantrips and low lv spells, while they are some like shocking grasp and shatter, I would love a cantrip that is like firebolt but lighting or thunder based, I know homebrew is a thing but I wish there were more lighting spell for the Tempest domain as a whole cause it's about using lighting and thunder but not many spells have those damage types

You can always go 2 levels in scribes wizard and change the damage types. Take shocking grasp and fire bolt as your wizard cantrips, and zap people with lightning. 

Edit: crap, you can’t do that it only applies when you use a spell slot, so no cantrips. But you could still take scribes and get more lighting spells. 

I mean, magic initiate to the Druid spell list has a few thunder and lightning damage cantrips

A shame that work past level 1 spells because the spell you are taking damage type from has to be same level and in your spellbook and at level 2, that is only level 1 spell slots (chromatic orb or witchbolt work for level 1 lightning damage):

• "When you cast a wizard spell with a spell slot, you can temporarily replace its damage type with a type that appears in another spell in your spellbook, which magically alters the spell's formula for this casting only. The latter spell must be of the same level as the spell slot you expend."

Maybe take 2 levels in sorcerer for metamagic for Transmuted at one sorcery point a pop. Second level sorcerer has 2 sorcery points and 3rd level has 3. You can also trade spell slots for metamagic points. Some campaigns start with bonus feat and metamagic adept gives you 2 more points.

Inflict wounds turned lightning damage is destructive.