Apple Watch Series 6
watchOS 7
1. Find "Watch Language"
On your phone: Press Watch.
On your phone: Press My Watch.
On your phone: Press General.
On your phone: Press Language & Region.
On your phone: Press Custom.
On your phone: Press Watch Language.
2. Select language
On your phone: Press the required language.
On your phone: Press Change to ‹language›.