Check out the Nitecore T4K. Not an 18650, but usb-c rechargeable, 4 brightness levels (1, 15, 65, and 200 lumens), plus a 4000 lumen turbo mode that it can maintain for about ten seconds before it has to drop back to 200 to cool down. Separate power and mode buttons, and it remembers what mode it was in when you turned it off. Great battery life, and small enough to fit in your pocket. The only downside is the price ($90), but.it’s worth every penny.