I spent time on this Amos, accept it as a subclass.

Restraining technique

Starting when you choose this tradition at 3rd level, you can gain the upper hand against the enemy in a fight. Whenever you hit a creature with one of the attacks granted by your Flurry of Blows, you can impose one of the following effects on that target:

• It must succeed on a Dexterity saving throw or be grappled
• It must succeed on a Dexterity saving throw or have disadvantage on any attacks it makes next turn
• It can't take bonus actions until the end of it's next turn

Pain of the Ancient Movements

At 6th level, you gain the ability to use your ki to help snap the neck of a grappled enemy. As an action, target creature you have grappled makes a Strength saving throw taking bludgeoning damage equal to three times your monk level on a failed save, or half as much on a success. This damage counts as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage. You must finish a long rest before you can use this feature again.

Outnumbered grapple

At 11th level, you can use your mastery of the mind and practice in ki and martial arts to grapple multiple enemies. As an action, expend 2 ki points to choose up to 4 creatures who are within 5 feet of you. The targets make a Wisdom saving throw, being grappled by you on a failed save or knocked back 5 feet on a successful one.

Defensive Manoeuvres

At 17th level, whenever a creature within 5 feet of you is hit by an attack made by a creature other than you, you can use your reaction to stop the attack and restrain that creature. Target creature makes a Strength saving throw and is restrained on a failed save. The restrained creature makes this throw with disadvantage and can spend it's turn trying to escape the restraint by repeating the saving throw. If a creature is restrained in this way, it's attack restrained deals no damage, but other effects from the attack still happen.