How to import photos on my iPhone on to Photos app on Mac in the Order of Date?

You may want check, if the date on your camera has been set correctly.

And if you have been abroad, in a country wit a different time zone, the timezone offset for the camera pictures may be wrong.

On your Mac:

• You may wat to collect all photos taken with your camera in an album and select all of them together with the keyboard shortcut ⌘A.
• Then use the command "Image > Adjust date & Time" to set the "time adjusted" to any offset, the date in the camera might have. Also set the closest city at the bottom of the dialog to a city in the timezone, where the photos have been taken. This may shift the "Time adjusted". set it back to the previously set value.

See the paragraph "Change a photo's Date & Time" on this page in the user guide: Add titles, captions and more to photos in Photos on Mac – Apple Support (UK)

Which part of the Photos app are you using to view your photos when you see them clumped that way? Each part has a predefined sort order or a set of sort orders that you can choose. None of the predefined orders is based on file name (DSCO... or IMG...) or source device type, so you must be seeing the effect of some other attribute of the photos.

For example, the All Photos view is supposed to display items in the order that the photos were captured (assuming the devices' clocks are set alike), and the Recents album is supposed to display items in the order that they were added to the library.

If you are already looking in All Photos and still seeing phone photos clumped separately from camera photos, you may be seeing a date or time zone mismatch.