Most models ship with a heavy 300W power brick, including RTX 3060 base models. Some RTX 3060 models and most RTX 3050/3050Ti models have been known to ship with 230W power bricks.

A good alternative confirmed to be fine with RTX 3070 models is the 240W GaN Charger by SlimQ, use coupon “laptopwikilegion2022” (affiliate link)

• 100W – Okay for charging, light to med productivity use but nothing too demanding
• 230W – Probably good enough for full productivity use in non extreme cases and get good performance. And most gaming should be okay. Definitely acceptable for RTX 3050-3060 models.
• 300W - Can be good if you want to get the most of it, have very demanding workloads or very demanding games. Recommended for RTX 3070 models and required for RTX 3080 models.

Short answer? Sort of.
Long answer: Our tests showed that a Legion with RTX3070 at TGP of 140W can pull up to 308W from the wall outlet. While during regular use, a weaker charger may be sufficient, when pushing the laptop to its limits, up to 300W of power can be drawn.
For example, by charging the battery while gaming in performance mode.
In other cases, if you don’t need charging while gaming, a regular original Lenovo 230W charger or SlimQ 240W charger should be sufficient for 5800H+RTX3070 models. In case of 5900HX+RTX3080, you may encounter battery drain if using 230W charger while gaming in performance mode. However, no performance loss should be encountered.

• 100W USB-C will work, however, greatly limit the dGPU, and no gaming should be expected.
  • USB Type C to Type C cable must be electronically marked to support 5 amps of current and the USBC source must be capable of 20V5A USB PD Output for 100W charging
• 65W USB-C charger will keep the laptop running, but not charging while turned on. It will slowly charge when laptop is asleep or turned off.
  • USB Type C to Type C cable must be electronically marked to support 5 amps of current and the USBC source must be capable of 20V3.25A USB PD Output for 65W charging
• 60W USB-C PD chargers should work, but only when the device is fully turned off, not in sleep/standby modes. — Thread#9227

Anything less is not likely going to work.
The rear USB-C port supports up to 100W USB-PD charging at 20V. Lenovo's proprietary 135W USB-C charger is confirmed to not work at full power on 2021 units, it will be limited to 100W.