How do I edit weight in iPhone 12 health app please

You cannot edit a weight entry directly. What you can do is delete a given weight entry and then manually add a correct entry.

To remove an incorrect entry, open the Health app ➡️ Browse ➡️ Body Measurements ➡️ Weight ➡️ Show All Data ➡️ Edit : Here you can select the incorrect weight entry by tapping on the red minus sign and then Delete.

You can then Add the correct entry manually by opening the Health app ➡️ Browse ➡️ Body Measurements ➡️ Weight ➡️ Add Data: Here, you can add the entry by selecting a date and the appropriate weight.

Axel F.

Please see the pic below which is self-explanatory