No it is a full or service size gun Firearm Specifications
Manufacturer: Walther
Model: PDP Full-Size
Caliber: 9mm Luger
Barrel Length: 4"
Slide Length: 7"
Height: 5.7"
Sights: White Dot; Adjustable
Trigger; Performance Duty Trigger
Magazine Capacity: 18 Rounds; Comes with Two
Weight (without magazine): 22.3 oz.
Slide Material: Steel
Frame Material: Polymer

The one your asking about is a duty size grip with 18+1 capacity, it has a compact 4" slide, the full size and duty size have 4½" slides and 5" slides respectively.
The true PDP Compact has a 4" barrel and a shorter 15+1 capacity with the shorter grip.
In stock here
budsgunshop.com/product_info.php/products_id/133692/walther+arms+2851229+pdp+compact+optic+ready+9mm+4+15%2b1+black+black+steel+slide+black+polymer+wperformance+duty+texture />-------------
There is also a compact grip with a full size 5" slide here
budsgunshop.com/product_info.php/products_id/135717/walther+arms+2844222+pdp+compact+optic+ready+9mm+5+15%2b1 />---------------
All versions come optics ready and all slides and grips are interchangeable with each other.

Nicole, it is full size, details here >>>>> https://waltherarms.com/pdp-full-size-4/ ....Have a great day!

Nicole, it has a 4 inch barrel so is considered a Service size handgun. Compacts will have a shorter than 4 inch barrel such as : budsgunshop.com/product_info.php/products_id/117927/springfield+armory+hellcat+osp+9mm+11%2b113%2b1+optic+ready

No, this is a full sized pistol., With a 4 inch barrel. So it's bigger than a compact but not too big I'd consider it mid-sized. Most of your compacts are going to have 3.5 inch barrels or less and probably more like 12 round magazines or less, so you know what to look for to find a compact pistol. Hope this helps.