op, it depends a lot on your child.
When my oldest was three, he walked like an 8 year old. My other son who’s 5, still walks like a 3 year old on the street. He’s veeery lazy and always exhausted!
It also depends, as mentioned above, how often you take far walks.
Don’t rush to buy one. Double strollers are very heavy and klutzy. I HATE to use mine. I use it only when I absolutely must. (For exapmle when going out to the seder and returning home at 3 in the morning.)
They sell buggy boards which connect to any standard stroller for an older child to stand on. Those are pretty good.