you could use vars like this,

mob/verb/say(t as text)
    usr <<"[size10][b][usr][endb]:[t]"

var/size1 = "<font size = 1>"
var/size2 = "<font size = 2>"
var/size3 = "<font size = 3>"
var/size4 = "<font size = 4>"
var/size5 = "<font size = 5>"
var/size6 = "<font size = 6>"
var/size7 = "<font size = 7>"
var/size8 = "<font size = 8>"
var/size9 = "<font size = 9>"
var/size10 = "<font size = 10>"
var/size11 = "<font size = 11>"
var/size12 = "<font size = 12>"
var/size13 = "<font size = 13>"
var/size14 = "<font size = 14>"
var/size15 = "<font size = 15>"
var/size16 = "<font size = 16>"
var/size17 = "<font size = 17>"
var/size18 = "<font size = 18>"
var/size19 = "<font size = 19>"
var/size20 = "<font size = 20>"
var/size21 = "<font size = 21>"
var/size22 = "<font size = 22>"
var/size23 = "<font size = 23>"
var/size24 = "<font size = 24>"
var/size25 = "<font size = 25>"
var/size26 = "<font size = 26>"
var/size27 = "<font size = 27>"
var/size28 = "<font size = 28>"
var/size29 = "<font size = 29>"
var/size30 = "<font size = 30>"
var/size31 = "<font size = 31>"
var/size32 = "<font size = 32>"
var/size33 = "<font size = 33>"
var/size34 = "<font size = 34>"
var/size35 = "<font size = 35>"
var/size36 = "<font size = 36>"
var/size37 = "<font size = 37>"
var/size38 = "<font size = 38>"
var/size39 = "<font size = 39>"
var/size40 = "<font size = 40>"
var/size41 = "<font size = 41>"
var/size42 = "<font size = 42>"
var/size43 = "<font size = 43>"
var/size44 = "<font size = 44>"
var/size45 = "<font size = 45>"
var/size46 = "<font size = 46>"
var/size47 = "<font size = 47>"
var/size48 = "<font size = 48>"
var/size49 = "<font size = 49>"
var/size50 = "<font size = 50>"
var/b = "<b>"
var/endb = "</b>"
var/i = "<i>"
var/endi = "</i>"
var/u = "<b>"
var/endu = "</u>"
var/s = "<s>"
var/ends = "</s>"