10,000mAh vs 20,000mAh
Do you need to recharge your iPhone more than 2 times before you can recharge the power bank? If yes, then go for a 20,000mAh model. If not then stick with 10,000mAh. There is a significant size and weight difference between the two. A 10,000mAh (if that’s enough) will be more comfortable on the job and on the go.
Anker PowerCore 10000 - Classic model, available at some Best Buys and Walmarts. Or just buy off Amazon. It is USB-A (regular Lightning cable) but supports Apple 2.4A. That is an old fast charging standard from Apple which is still on newer model iPhones. So if the iPhone is near 0% it’ll charge up to 10.5W vs the usual 5W. A USB-A only charger will also last you a bit longer. It uses lower voltage, so less power is loss in the voltage conversion process.
Anker PowerCore 10000 PD - Newer model with USB-C and Power Delivery support. Newer iPhones like yours support Power Delivery for fast charging. It can get up to 15W. Compared to Apple 2.4A the newer PD is faster from 0-30% and almost the same from 30-50%. From 70-100% all fast charging is turned off. Its USB-A port also supports Apple 2.4A. So you could fast charge two iPhones at once. Though the power bank wouldn’t make it past a single recharge for each.
The older model is cheaper and will work fine for your needs. The newer PD model is a bit faster, in exchange for a bit less power (or use the USB-A port to conserve power when needed). PD model is also better future proofed.
Top: Anker PowerCore 10000. Bottom: Anker PowerCore 10000 PD.
Lot of choices, too many to go through.
If you want USB-C then go for the PowerCore Speed 20000 PD. You can get just the power bank and USB-C cable from Walmart. Or a bundle including a 30W USB-C wall charger from Amazon or Best Buy. The wall charger will charge your iPhone well, so dedicated travel charger?
Other USB-C models from Anker are either more expensive, non-PD, and/or have features beyond what you need for an iPhone.
If you want cheaper any Anker 20,000mAh power bank with PowerIQ will support Apple 2.4A fast charging.