frame-size-history is a variable defined in ‘C source code’.
Its value is shown below.

Documentation:
History of frame size adjustments.
If non-nil, list recording frame size adjustment.  Adjustments are
recorded only if the first element of this list is a positive number.
Adding an adjustment decrements that number by one.

The remaining elements are the adjustments.  Each adjustment is a list
of four elements ‘frame’, ‘function’, ‘sizes’ and ‘more’.  ‘frame’ is
the affected frame and ‘function’ the invoking function.  ‘sizes’ is
usually a list of four elements ‘old-width’, ‘old-height’, ‘new-width’
and ‘new-height’ representing the old and new sizes recorded/requested
by ‘function’.  ‘more’ is a list with additional information.

The function ‘frame--size-history’ displays the value of this variable
in a more readable form.

Value:
(967
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-1
	  (1820 1680 1820 1680)
	  (set-window-configuration 1))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-3
	  (1120 1080 1820 1680)
	  (1149 1080 1849 1680))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-1
	  (1120 1080 1820 1680)
	  (change-frame-size 5))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> xg-frame-resized
	  (1120 1080 1120 1080)
	  nil)
 (#<frame emacs@rpluim-ubuntu 0x133fd20> xg-frame-set-char-size-3
	  (1120 1080 1120 1080)
	  (1149 1183))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-2
	  (1120 1080 1120 1080)
	  (nil nil))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-1
	  (1120 1080 1120 1080)
	  (tool-bar-lines 2))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> update-frame-tool-bar nil nil)
 (#<frame emacs@rpluim-ubuntu 0x133fd20> xg-frame-resized
	  (1120 1080 1820 1680)
	  nil)
 (#<frame emacs@rpluim-ubuntu 0x133fd20> xg-frame-set-char-size-3
	  (1120 1080 1820 1680)
	  (1849 1725))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-2
	  (1120 1080 1820 1680)
	  (nil nil))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-1
	  (1120 1080 1820 1680)
	  (x-set-frame-parameters 1))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> "FRAME-NOTICE-USER" nil
	  ((height . 56)
	   (width . 130)
	   (left . 0)
	   (top . 0)))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> "MAKE-FRAME")
 (#<frame emacs@rpluim-ubuntu 0x133fd20> x-handle-net-wm-state nil
	  (nil nil))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> x-handle-net-wm-state nil
	  (nil nil))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> x-handle-net-wm-state nil
	  (nil nil))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> x-handle-net-wm-state nil
	  (nil nil))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> x-handle-net-wm-state nil
	  (nil nil))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> xg-frame-resized
	  (1120 1080 1120 1080)
	  nil)
 (#<frame emacs@rpluim-ubuntu 0x133fd20> x-set-fullscreen nil
	  (nil nil))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-1
	  (1120 1080 1120 1080)
	  (xg-frame-set-char-size 5))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> xg-frame-set-char-size-3
	  (1120 1080 1120 1080)
	  (1149 1125))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-2
	  (1120 1080 1120 1080)
	  (nil nil))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-1
	  (1120 1080 1120 1080)
	  (x-create-frame-2 0))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-1
	  (1120 1080 1120 1080)
	  (menu-bar-lines 2))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-1
	  (1120 1080 1120 1080)
	  (scroll-bar-height 3))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-3
	  (1120 1080 1120 1080)
	  (1136 1080 1149 1080))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-1
	  (1120 1080 1120 1080)
	  (scroll-bar-width 3))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-3
	  (10 10 140 300)
	  (10 10 156 300))
 (#<frame emacs@rpluim-ubuntu 0x133fd20> adjust-frame-size-1
	  (10 10 140 300)
	  (x-create-frame-1 5))
 (#<dead frame F1 0xc89040> adjust-frame-size-3
	 (10 10 10 9)
	 (10 10 10 10))
 (#<dead frame F1 0xc89040> adjust-frame-size-1
	 (10 10 10 9)
	 (change-frame-size 5)))