Cannot find the Apple One on my iPhone settings no matter how many times I restart. Anyone know any other way to subscribe?

you have to downgrade your iCloud 50GB to none if you only need 50GB when you sign up Apple One
the reason is Apple One Individual bundled with 50GB, on top of this you can freely sign up additional 50GB(RM3.90) or 200GB(RM11.90) or 2TB(RM39.90), making total 100GB/250GB/2.05TB
unlike bundles inside Apple One where Apple Music, Apple Arcade and Apple TV+ is only ONE to subscribed

if you choose not to downgrade your existing 50GB to none, what you actually paying after Apple One trial is RM19.90 (individual) + iCloud 50GB (RM3.90), thus, it makes your iCloud to 100GB in total

if you choose to downgrade your iCloud 50GB will last until 17th Nov.... will grant you having 100GB until 17th Nov after that will back to 50GB (which comes with Apple One)
https://support.apple.com/en-us/HT207594 if you downgrade, it stills give u 2TB tils your current subscription ends
e.g.: your iCloud subscription renew every 15th monthly, if you downgrade now, 2TB stayed until 15h Nov