Android brand paths (menu names may vary)

OPPO / realme / OnePlus: Settings → Home screen, Lock screen & Personalization → tap Time → choose clock color
vivo / iQOO: Settings → Home screen, Lock screen & Wallpaper → Lock screen → tap Time → clock color (OriginOS 4+)
Xiaomi / Redmi: Settings → Wallpaper → Lock screen & Home → clock color; or long-press time on home screen → Customize
Huawei / Honor: Settings → Home screen & personalization → System colors → lock screen & home clock color
Samsung: Set a gallery photo as lock wallpaper first → change time color in the system dialog → then subscribe in 92 Wallpaper