He just closes and opens the lid. Is this behaviour recommended and healthy for my new Windows laptop or does it harm the laptop in any way?

This does not harm the laptop in any way. I have done this many times. No issue.

Alternative 1: It is a Lenovo machine. Install Lenovo Vantage and set Battery Threshold to Max 80% Min 75% and then you can leave the machine ON and not suspended. Battery lifespan is not harmed doing this. (Nor is Battery lifespan extended)

Alternative 2: Suspend at end of day, but do start up the next day. If you Suspend and ignore the computer for a very long time (week or so) the battery will wear down.

Alternative 3: Enable Hibernate and hibernate for long periods.

I use Alternative 1 and usually shut down on a weekend evening.

Remember, you do have to update monthly at least and restart anyway at that time.

He just closes and opens the lid. Is this behaviour recommended and healthy for my new Windows laptop or does it harm the laptop in any way?

This does not harm the laptop in any way. I have done this many times. No issue.

Alternative 1: It is a Lenovo machine. Install Lenovo Vantage and set Battery Threshold to Max 80% Min 75% and then you can leave the machine ON and not suspended. Battery lifespan is not harmed doing this. (Nor is Battery lifespan extended)

Alternative 2: Suspend at end of day, but do start up the next day. If you Suspend and ignore the computer for a very long time (week or so) the battery will wear down.

Alternative 3: Enable Hibernate and hibernate for long periods. Hibernate writes an image of the working system to disk (hiber file) so that it can save more power when hibernated.

I use Alternative 1 and usually shut down on a weekend evening.

Remember, you do have to update monthly at least and restart anyway at that time.