Unlock keypad for Phone Lock

If you meant that you want to change from this↓

to this…↓

then all you need to do is

1. Go to Settings > Touch ID& Passcode > enter your current passcode
2. Tap Change Passcode > enter your current passcode
3. Now make sure you see 6 circles on the “Enter New Passcode” screen, (or 4 circles if you choose 4-digit numeric code)
4. Enter your new desired (numerical-only) passcode twice, and you’re good!

It would be better if you can please re-post with a screenshot, in order to understand the phenomenon better. Images / pictures speak louder than words. Do not provide any personal credentials, such as email id, apple id, IMEI number, Serial Number, Phone number, Order ID, if you are sharing a map ensure your location is not identifiable. Etc.