Ningguang is a Geo elemental type character that can deal huge burst damage in a short period of time, while also providing some small support. Her elemental skill doubles as a wall that blocks projectiles, but can also be used to deal extra damage if you use her elemental burst when it's up. Since her elemental burst has low energy cost, you will occasionally be able to fire them off multiple times in a prolonged fight. She can also be effective at being your primary damage dealer since her normal attacks are quite fast.
Despite not having elemental reaction that deals damage, Ningguang can still fit the role of a main damage dealer. For artifacts, the two best options are either 2 piece Archaic Petra with 2 piece Gladiators Finale, or 4 piece Retracing Bolide. 4 piece Archaic Petra is not recommended since she can't get a Crystalized Geo element shield on her own. 4 Retracing Bolide has a conditional requirement, that can be somewhat tricky to manage, but it does deal more damage than the 2 piece mix set. However, for consistent result and ease of use, the 2 piece mix of archaic petra and gladiator is the better choice. Make sure to use Geo damage increase on the cup piece, and crit rate/damage up on the crown.
For weapons, Lost Prayer to the Sacred Winds is the best one to use for her. Solar Pearl is a very close second choice, and a lot easier to obtain compared to relying on the gacha. Memory of Dust, a weapon that has its own banner, is also a very solid option to use for her. The other optional weapons that you can use are The Widsith, or Eye of Perception.
She can be a second dps unit that you switch to for a quick burst when her elemental burst is up. This can be an option to consider if you don't have the best gear for her. 4 piece Archaic Petra can boost the damage of your main damage dealer, even if you just put a level 1 set. 4 piece Noblesse Oblige works too, or just use 2 piece artifact sets with +18% attack. If you are strictly using her as the second dps, you can use energy recharge on the hourglass for quick up time on her elemental burst so she can use it more often.
For weapons, it's mostly the same as the dps build, or just use weapons with energy recharge as the secondary. Prototype Malice
is worth mentioning, since it can help your team if you don't have a dedicated healer in your party. If you use it sparingly, she can be a consistent healer on the team.
Since she doesn't have a good elemental synergy with the others, she can essentially be put on any team, but also not work amazingly well either. Geo elemental resonance is a nice bonus, but it's not worth focusing on since it requires a shield and the bonus is lower than double Pyro on the team. But having 2 Geo can still help with energy gain, so consider bringing them if you have any of the other Geo characters leveled up. Characters like Beidou and Xingqiu can be a nice pair since their elemental burst helps deal damage, and works even when you switch out of them. Other really good options are Bennett, Mona, and Fischl.
"Normal Attack Shoots gems that deal Geo DMG. Upon hit, this grants Ningguangg 1 Star Jade.
Charged Attack Consumes a certain amount of Stamina to fire off a giant gem that deals Geo DMG. If Ningguangg has any Star Jades, unleashing a Charged Attack will cause the Star Jades to be fired at the enemy as well, dealing additional DMG.
Plunging Attack Gathering the might of Geo, Ningguang plunges towards the ground from mid-air, damaging all enemies in her path. Deals AoE Geo DMG upon impact with the ground."