Do the maximum allowed dimensions of parcels that I want to have collected by the Collection Service differ from the standard maximum parcel dimensions?

That depends on the carrier and pickup service you choose.
 

PostNL

• MyParcel Pick-up: The maximum size of parcels (up to 25 parcels) is 50 x 40 x 35 cm.
• Pick-up Plus: The maximum size of parcels is 175 x 75 x 58 cm.

DPD
The maximum length is 175 cm. The maximum girth is 300 cm.
The maximum weight is 31.5 kg.

UPS
The longest side can be a maximum of 274 cm.
The maximum weight is 70 kg.

For DHL, the same dimensions apply when you drop off the parcels at a pickup location as when you have them picked up with a pickup service.

Please note! The carrier only picks up parcels that actually have a label from that carrier. For example, you cannot give PostNL parcels to a DPD pickup service.