802.11k, 802.11r, and 802.11v are integral in improving the the experience of Wi-Fi clients, specifically around mobility and roaming. Mist supports all three. Ultimately roaming is the decision of the client, however the infrastructure can help the client to make better roaming decisions
802.11k helps clients discover neighboring APs, reducing the need for the client to perform off-channel scanning as it makes the decision on the next Access Point to roam to. A client will request a list of neighboring APs in the form of a neighbor report. 802.11k is enabled by default
802.11r helps clients roam more quickly from one AP to another. 802.11r can be enabled on a per WLAN basis and is generally recommend on PSK and 802.1X WLANs.
802.11v is a large amendment, which consists of several features, most of which were never implemented in the real world. Mist supports 802.11v BSS Transition Management (BTM), it is enabled by default. 802.11v BTM allows the infrastructure to make solicited or unsolicited roaming recommendations to the client. Which the client is free to ignore, and they often do.