Japt -R, 23 bytes

Includes a trailing space on each line of output.

Æ"+= "¬ËiMg°XÃvÈùT±XÊì

Try it

Japt -mR, (削除) 23 (削除ここまで) 22 bytes

Includes a trailing space on each line of output.

"+= "¬ËiMg°UÃvÈùT±XÊì

Try it

"+= "¬ËiMg°UÃvÈùT±XÊì :Implicit map of each U in the range [0,input)
"+= "¬ : Split "+= " to an array of characters
 Ë : Map
 i : Prepend
 °U : Prefix increment U
 Mg : Get the Uth Fibonacci number, 0-indexed
 Ã : End map
 v : Modify the first element
 È : By passing it through the following function as X
 ù : Left pad with spaces to length
 T± : Increment T (initially 0) by
 XÊ : Length of X
 Ã : End modification
 ¬ : Join
 :Implicit output joined with newlines