The human vs alien arms race is the heart of XCOM and XCOM 2. You pour resources into better armour and weapons to keep pace with the enemy. Now you can escalate that race even further with War of the Chosen Tank Mod (opens in new tab).
The mod adds massive tanks which serve as their own class with a full upgrade tree that unlocks special abilities. The tanks are incredibly durable, but tend to malfunction when they overheat. Advent can also access tanks, so bring some good armour piercing upgrades into your battles.
Modder Giuseppelll says "Enemy ADVENT tanks will start appearing at force level 19 and start stronger than the baseline player controlled tanks. These, while tough, are incredibly fun late game units to beat!"
Special abilities include 'Death Spiral', in which the tank deploys lasers and donuts to hit everything within the laser's range. That's just a mid-tier ability. In the first round of ability progression you can unlock 'Concentrated Beam' which allows the laser attack to also set targets on fire. You can also release pent-up heat with the 'Vented Flamethrower' attack. That's just how futuristic tanks like to chill.
The tanks are huge, and tend to destroy any terrain they collide with. Here's how to get one: "You can purchase player controlled tanks in the proving grounds for 500 supplies, 100 alloys and 4 elerium cores. These values can all be configured in Xcomgamedata.ini including the ability to require having parts of ADVENT tanks before you can build one yourself."
Giuseppelll has created a range of mods for XCOM 2: War of the Chosen, including extra national voices and more mission types. Check them out on the Steam Workshop profile (opens in new tab), and see the tank in action in the video below. Skip to 5:30 to see it.