but branch new <name>?
but branch new -A/--above <commit or branch>
but branch new -B/--below <commit or branch>
but branch new --format human/json/shell

Example baseline

┊╭┄op [top]
┊●   20e235d six
┊●   e28a167 five
┊│
┊├┄mi [middle]
┊●   58410cd four
┊●   5a08eb5 three
┊│
┊├┄bo [bottom]
┊●   87a11e5 two
┊●   28e6961 one
├╯

Above/below branches

but branch new

┊╭┄op [top]
┊●   20e235d six
┊●   e28a167 five
┊│
┊├┄mi [middle]
┊●   58410cd four
┊●   5a08eb5 three
┊│
┊├┄bo [bottom]
┊●   87a11e5 two
┊●   28e6961 one
├╯
┊
┊╭┄dp [canned]
├╯

but branch new foo

┊╭┄op [top]
┊●   20e235d six
┊●   e28a167 five
┊│
┊├┄mi [middle]
┊●   58410cd four
┊●   5a08eb5 three
┊│
┊├┄bo [bottom]
┊●   87a11e5 two
┊●   28e6961 one
├╯
┊
┊╭┄dp [foo]
├╯

but branch new --above bottom

┊╭┄op [top]
┊●   20e235d six
┊●   e28a167 five
┊│
┊├┄mi [middle]
┊●   58410cd four
┊●   5a08eb5 three
┊│
┊├┄mi [canned]
┊│
┊├┄bo [bottom]
┊●   87a11e5 two
┊●   28e6961 one
├╯

but branch new --below bottom

┊╭┄op [top]
┊●   20e235d six
┊●   e28a167 five
┊│
┊├┄mi [middle]
┊●   58410cd four
┊●   5a08eb5 three
┊│
┊├┄bo [bottom]
┊●   87a11e5 two
┊●   28e6961 one
┊│
┊├┄bo [canned]
├╯

but branch new --above top

┊╭┄op [canned]
┊│
┊├┄op [top]
┊●   20e235d six
┊●   e28a167 five
┊│
┊├┄mi [middle]
┊●   58410cd four
┊●   5a08eb5 three
┊│
┊├┄bo [bottom]
┊●   87a11e5 two
┊●   28e6961 one
├╯

Above/below commits

but branch new --above 5a08eb5

┊╭┄op [top]
┊●   20e235d six
┊●   e28a167 five
┊│
┊├┄mi [middle]
┊●   58410cd four
┊│
┊├┄mi [canned]
┊●   5a08eb5 three
┊│
┊├┄bo [bottom]
┊●   87a11e5 two
┊●   28e6961 one
├╯

but branch new --below 5a08eb5

┊╭┄op [top]
┊●   20e235d six
┊●   e28a167 five
┊│
┊├┄mi [middle]
┊●   58410cd four
┊●   5a08eb5 three
┊│
┊├┄mi [canned]
┊│
┊├┄bo [bottom]
┊●   87a11e5 two
┊●   28e6961 one
├╯

but branch new --above 58410cd

┊╭┄op [top]
┊●   20e235d six
┊●   e28a167 five
┊│
┊├┄mi [middle]
┊│
┊├┄mi [canned]
┊●   58410cd four
┊●   5a08eb5 three
┊│
┊├┄bo [bottom]
┊●   87a11e5 two
┊●   28e6961 one
├╯