Voluntry bans: is there a limit of how long and short a voluntry ban can be?

i know when moderators and admin ban someone, they choose how long its for, if we ask for one do we get to choose how long or short its for? or do they choose?

idk, dare not ask in a new thread

i can block the site on the older laptop, not sure about this laptop, i cant block sites on my "smart" phone though cause it will not do it