M-x customize face RET по умолчанию позволит вам установить грань default
face, на которой основаны все остальные грани. Там вы можете установить размер шрифта.
Вот что есть в моем .emacs. на самом деле, color-theme установит основы, а затем моя пользовательская настройка лица отменит некоторые вещи. custom-set-face записывается с помощью механизма emacs customize-face:
;; my colour theme is whateveryouwant :)
(require 'color-theme)
(color-theme-initialize)
(color-theme-whateveryouwant)
(custom-set-faces
;; custom-set-faces was added by Custom.
;; If you edit it by hand, you could mess it up, so be careful.
;; Your init file should contain only one such instance.
;; If there is more than one, they won't work right.
'(default ((t (:stipple nil :background "white" :foreground "black" :inverse-video nil :box nil :strike-through nil :overline nil :underline nil :slant normal :weight normal :height 98 :width normal :foundry "unknown" :family "DejaVu Sans Mono"))))
'(font-lock-comment-face ((t (:foreground "darkorange4"))))
'(font-lock-function-name-face ((t (:foreground "navy"))))
'(font-lock-keyword-face ((t (:foreground "red4"))))
'(font-lock-type-face ((t (:foreground "black"))))
'(linum ((t (:inherit shadow :background "gray95"))))
'(mode-line ((t (nil nil nil nil :background "grey90" (:line-width -1 :color nil :style released-button) "black" :box nil :width condensed :foundry "unknown" :family "DejaVu Sans Mono")))))