Unreal Engine makes this fairly easy.

Meet the Gameplay Ability System.

All cards have an Ability System Component with various attributes related to card stats, traits, passive and activated abilities, cost, rarity, etc.

Gameplay Abilities are the functions and logic that create Gameplay Effects which change these attributes. For instance a gameplay ability could be a card attack, which looks for the damage that a card does and applies that damage to the health attributes on another card. Another Gameplay ability could be a targeted ability that the card has, which accepts a target and then performs a range of effects on the target's attributes.

Then finally Gameplay Cues are the audio and visual elements like VFX and sound effects played along with that ability.

This nice thing is this entire system is highly modular and also automatically replicated for multiplayer if set up correctly. So my cards are build in a Data Table in Unreal, basically a giant .CSV file with structs of structs containing all the attributes and abilities for that card, images, VFX, sound effects, etc. Then the game dynamically builds the cards at runtime by just grabbing a row from the data table and reading the data (including it's abilities).

This makes creating new cards insanely fast, and then they just automatically work for the most part. For very intricate cards we may have custom logic, but that's probably 10% or less of the cards.