Hi and welcome !.
I owned a PHEV for four years, before going full BEV in 2019.
Most PHEV owners are likely to charge from empty to full all of the time, the battery is SO small that this is the only way to make full use of that small amount of electric power, thus saving on fossil fuel.
I guess your max range reported, will be around 30 miles ( as it was on my previous car ).
After you have owned the car for a few years, you will see that predicted range reduce slightly, yes.
But it is less important, because you have the engine as a back up.
My car would report a EV range of 32 miles when new.
When I sold the car after four years and about 30,000 miles, that range ( after a full charge ) had reduced to around 27 miles.
Of course, your predicted range in the summer months, will be more than the winter months.
Your MPG will be less also, this is no different to a BEV or to fossil cars.
Its unavoidable, so just charge to full and enjoy the car, without worrying about the effects on the HV battery health.
If you try to treat your battery kindly, by not letting run to zero and then not charging to full, then your EV mileage is going to very short, and frankly not worth bothering with !.
So, follow other PHEV owner ( like myself at one time ) and just charge and go !.