You mean make them start & end slower than regular walk speed? Or do you mean you want to play a start & end walk animation on begin & end of walking?
Multiple character outfits could be one way to go for sorting out the walk stuff or maybe multiple walk animations inside of the same outfit which you change between using the change character animation index value. Or if you are using the default sliding walk system, then you could adjust the characters walk speed, maybe with the Lua to() tweening function. Not really sure how you would sort out the speed of the ending walk animation with that as you would need a loop to listen out for when character is x distance from destination. But init walk would be easy enough as you could use a condition or something & insert the to() tween inside of the first frame of each walk animation or use a Loop to listen out for when character starts walking.
game.CurrentCharacter.CurrentOutfit.OufitCharacterSpeed = 200 -- set initial speed value
game.CurrentCharacter.CurrentOutfit:to(3000, {OutfitCharacterSpeed = 300}, easeQuintIn) -- change to 300 over 3 seconds.