A child cannot be toilet trained until they are ready both physically and emotionally, irrespective of their age.
The process can be speeded up by the use of an effective award system, which is used immediately after every success on the potty.
Rewards can be chosen that will motivate your child and also to comply with your own feelings on the matter.
Always give verbal praise as well as any other reward.
Imagination is needed to find a suitable reward for your child and if success is not apparent, try changing the reward to one which might be more motivating to them or wait a few more weeks and then try again.
If a reward system is used then begin to fade it out after a few weeks and you “forget” to give it to them or “run out” of it occasionally and only give it if they ask for it, until it can be accepted that verbal praise is sufficient reward in itself.