How to safely shut down or force shut down Oppo devices

Oppo R15 Neo Oppo R15 Neo
Oppo AX5 Oppo AX5
Oppo R17 Neo Oppo R17 Neo
Oppo AX7 Pro Oppo AX7 Pro
Oppo AX5s Oppo AX5s
Oppo Reno Lite Oppo Reno Lite
Oppo A5s Oppo A5s
Oppo Reno Z SD710 Oppo Reno Z SD710
Oppo Reno Z Helio P90 Oppo Reno Z Helio P90
Oppo Reno Z Oppo Reno Z
Oppo K3 Oppo K3
Oppo A9x Oppo A9x
Oppo A1k Oppo A1k
Oppo Reno 5G Oppo Reno 5G
Oppo A9 Oppo A9
Oppo A7n Oppo A7n
Oppo Reno Oppo Reno
Oppo Reno 10x zoom Oppo Reno 10x zoom
Oppo A5s (AX5s) Oppo A5s (AX5s)
Oppo F11 Oppo F11