You can't customize how much applications would be displayed in the "Frequently Used Apps" card under "Your Feed". It feels like part of functionality responsible for that is missing.
The only inherited property is icon. It is inherited from icon set in "App drawer". All other settings like size, elements per row/column, how much rows should be displayed, filters allowing you to sort apps passing into and so on is missing.
In my particular case the card has four columns. Everywhere else (Dock, Home etc) I set MS launcher to use 7 columns.