One of those is mx500 shell and one is pk/docomo shell. So you will certainly do well to get both and see which fits best. Of course mx500 shells open up much more variety of choice but some with smaller ears much prefer the pk size shell.
As for foams, stock foams we consider 'full foams' or 'donut foams' which are medium density medium thickness and they are the standard choice. The difference is one has a cut out middle and lets through more high frequency. Both have roughly similar bass quantity.
Then there's thick foams like hiegi full/donuts or VE donuts. They work better for slightly bigger ears or to make a better seal. Whether these will add more or less bass really depends on your ear anatomy, results vary from person to person. One constant though is that the add slightly more space between the driver and ear. So this in theory can help add more soundstage at the cost of some low midrange fullness.
Finally there are thin foams like the VE ex pack thins and the aliexpress black thins. These are the most open sounding letting more highs and only barely adding some bass quantity. I find these work best on warm bassy earbuds, they keep the 'no foam' clarity whilst adding a slight seal and comfort, keeping the earbud anchored better in your ear.
Here's the links to foams. I suggest you buy them all.
Thin foams
https://s.click.aliexpress.com/e/cg6plESy
Heigi donuts
https://s.click.aliexpress.com/e/cSFhvxDW
Heigi fulls
https://s.click.aliexpress.com/e/bVPYwhZe
Various colour regular donuts and full foams
https://s.click.aliexpress.com/e/cOfllfwY
https://s.click.aliexpress.com/e/cXn81rGy
The whole lot will set you back like $10-15. It's worth it. Imagine headphone earpads were that cheap to roll