You can disable Safari using the "Screentime" restrictions. Having to go into Settings, find the Screentime section, enter a passcode and find the setting to r

You can disable Safari using the "Screentime" restrictions. Having to go into Settings, find the Screentime section, enter a passcode and find the setting to re-enable Safari may provide enough of a effort barrier that you don't bother with whatever thing it was that sprang to mind as a potential distraction. For even more effective control, let someone else set your Screentime passcode :)