I have an iPhone SE under iOS 12.3.1 and I would like to be able to lock my iPhone using the home button by holding the button for instance. My lock button isn’t responding for a while and Assistive Touch is quiet annoying for a small screen like mine. Any suggestions? Thanks a lot.
It's not possible to use Home button to lock your iPhone. If your iPhone's lock button is broken, using assistive touch is your only resort.
You can optionally set up your iPhone to auto-lock. The minimum duration you can set for auto-lock is 30 seconds.