How do I increase size of Virtual Memory in Mac OS Catalina?
The short answer, is you do nothing. The system decides what memory gets swapped to disk and allocates space as needed. The system allocates virtual memory addresses up to ~18 exabytes so that it can then swap as needed.

Note: Unlike most UNIX-based operating systems, OS X does not use a preallocated disk partition for the backing store. Instead, it uses all of the available space on the machine’s boot partition.

You may just have to choose programs that use macOS better if your system is in memory pressure and you can’t wait for things to work. Virtual memory and swap guarantee that programs eventually run when you over load the actual resources available. There is no need to change any tuning or limits on iOS or macOS.
Even better, containers let you share space and not get jammed with pagefile.sys blocking space. I recommend exactly what you propose, APFS containers to share all possible space. Add an inexpensive external drive and let time machine back everything up so you are free to experiment without losing any games or data.