The only way to increase the IGPU vRAM is through BIOS Settings in laptop.
Many Laptop Manufacturers doesn't allow Users to change the vRAM on their laptop IGPU in BIOS Settings.
But if you laptop does have that option than it also depends on how much System RAM your laptop has installed.
vRAM takes away physically your System RAM to be used exclusively by the IGPU. If you increase your vRAM to 2GB and you have 8GB of System Ram then your laptop will now only have 6GB of System RAM to use.
Generally 512mb seems to be the default setting in most laptops. Windows will automatically allocate the amount of System RAM your IGPU will need to run any apps and then return it back to System RAM once the app is closed.
Adding more vRAM to your IGPU will make your IGPU run more efficiently.
Here is your HP SUPPORT Download page for your laptop: https://support.hp.com/us-en/product/details/hp-pavilion-15.6-inch-laptop-pc-15-eh1000/model/2100286...
Looks like your HP laptop has 16GB of System RAM so you should easily be able to add more vRAM to your IGPU if it is supported in BIOS.
Downloading and looking at your HP User Guide it doesn't have a BIOS section so I can't help you since I don't know if your laptop supports that setting in BIOS or not.
Open a HP SUPPORT ticket and ask them directly would be the best bet or open a HP Forum thread or just wait until you get your laptop and go to BIOS settings and see if you can increase vRAM in BIOS or not.
