The 512M is a frame buffer -- not the video RAM.   Depending on the total amount of system RAM, Windows will adjust allocation between the system and the video RAM.

Most often, applications that read the 512M as the video RAM require true, dedicated video RAM.  Your system has none -- though systems that have AMD or nVidia GPUs typically do have this, and that's what the application is looking for.  In that case, what you need is a different system with a discrete GPU -- no allocation of video RAM will enable a feature your system does not have.

 

According to the recommendation from AMD, UMA Frame Buffer Size should be AUTO. If DELL is not willing to provide the customers an option to change the UMA Frame Buffer Size in the BIOS, can this be at least be confirmed that this UMA Frame Buffer Size on these High Performance Ryzen 5500U Vostro 5415 is set to AUTO (as recommended by AMD)?

 

This is the recommendation from the people who gave us the great AMD Ryzen 5500U and many others (found here: https://www.amd.com/en/support/kb/faq/pa-280

 

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The UMA Frame Buffer Size when set to Auto (default setting) allows the system to manage the amount of shared memory for graphics. In this configuration, the size of the UMA frame buffer should scale depending on the amount of available system memory, enabling the system to perform in an optimal state. Therefore, it is recommended to leave the setting on Auto, which is ideal for most types of video processing workloads.

That being stated, some games may not yet be optimized for integrated graphics. In such cases, missing and/or low-resolution textures could be observed in game, or a warning message about the GPU not meeting requirements may appear during launch. These issues could be potentially resolved by manually setting the UMA frame buffer size. As an example, for systems equipped with 8GB of RAM or more, set the UMA buffer size to 1GB or 2GB.

Of course you can increase UMA_Buffer.

There is a method described here. https://youtu.be/0jwrWCF5fhc

In short this utility that changes hidden bios setting, including amd cbs. you will need to create free dos flash drive and write this utility to the flash drive. Don't forget to disable secure boot in bios prior to booting from flash.

I can confirm this method works for 5415 8 core ryzen laptop.

Got to AMD CBS ->nbio common options.

Set iGPU settings to UMA_Specified, and memory size to what you want,

I set it to 2 gb. Now Illustrator can zoom with GPU. (If Illustrator sees VRAM equal 512 it thinks your gpu is outdated and you work on CPU with lags)