Hi @aida_lover , I am from Hermanus and could recommend some trails. For mountain hiking, have a look at Fernkloof Nature Reserve (very easy walking). You can also do the Cliff Path walk which is magnificent. Another option is to do a round loop of the cliff path and the mountain by walking through the town to link the two (up to 20km). Navigation is very very easy, the trails are available on most offline map apps like Maps.me or Avenza Maps. Cliff path schematic map is available via Google.
In Franshhoek there is also the Mont Rochelle Nature Reserve. Havent done it, but apparently hiking there is very nice (“Perdekop” is the highest peak, approx. 1500m ASL, I think its 15km but not sure). You should be able to find maps on Maps.me or Avenza Maps.
For Cederberg, please consider buying the Slingsby map series (Google or in SA bookshops). Also consider using Avenza Maps. You have to download the local topographical maps via the app (they are free), may be hard to understand if you dont know our map system. They have strange names in this format - “3319 AD Keerom” (location codes and then a name). You will have to locate the Cederberg area on a general map of SA inside the app, click on the required map and then download it for offline use. But the app works VERY well with a GPS phone. I tested the app against a Garmin Etrex, and I prefer using the app. It overlays your position on the official surveyed 1:50000 topographical maps of South Africa - you can take bearings, measure distances, record placemarks and routes, etc.