I’ve been happy with this one. I’ve had it for a couple of years and only use it once in a while but its worked well. Also, it was very inexpensive for the size and fast charging ability. I keep it in my bag for those times when I didn’t have an outlet nearby. It also has a lot of good reviews.

POWERADD EnergyCell Ⅱ 10000 High-Speed Charging Portable Charger PD 18W, 10000mAh Power Bank USB-C Power Delivery (18W) for iPhone 11Pro Max 8 X XS, Samsung S10 Pixel 3XL and More https://www.amazon.com/dp/B07Y9NMBFB/ref=cm_sw_r_cp_api_glc_fabc_0bf8Fb330RRSB?_encoding=UTF8&psc=1