Don’t they already do for fonts (sort-of)?
http://www.ecma-international.org/publications/files/ECMA-ST..., section 8.3.53:
FNT - FONT SELECTION
Notation: (Ps1;Ps2)
Representation: CSI Ps1;Ps2 02/00 04/04
Parameter default values: Ps1 = 0; Ps2 =0
FNT is used to identify the character font to be selected as primary or alternative font by subsequent occurrences of SELECT GRAPHIC RENDITION (SGR) in the data stream. Ps1 specifies the primary or alternative font concerned:
0 primary font
1 first alternative font
2 second alternative font
3 third alternative font
4 fourth alternative font
5 fifth alternative font
6 sixth alternative font
7 seventh alternative font
8 eighth alternative font
9 ninth alternative font
Ps2 identifies the character font according to a register which is to be established.
Also, section 8.3.55 and 8.3.56:
8.3.55 GSM - GRAPHIC SIZE MODIFICATION
Notation: (Pn1;Pn2)
Representation: CSI Pn1;Pn2 02/00 04/02
Parameter default values: Pn1 = 100; Pn2 = 100
GSM is used to modify for subsequent text the height and/or the width of all primary and alternative fonts identified by FONT SELECTION (FNT) and established by GRAPHIC SIZE SELECTION (GSS). The established values remain in effect until the next occurrence of GSM or GSS in the data steam.
Pn1 specifies the height as a percentage of the height established by GSS
Pn2 specifies the width as a percentage of the width established by GSS
8.3.56 GSS - GRAPHIC SIZE SELECTION
Notation: (Pn)
Representation: CSI Pn 02/00 04/03
No parameter default value.
GSS is used to establish for subsequent text the height and the width of all primary and alternative fonts identified by FONT SELECTION (FNT). The established values remain in effect until the next occurrence of GSS in the data stream.
Pn specifies the height, the width is implicitly defined by the height.
The unit in which the parameter value is expressed is that established by the parameter value of SELECT SIZE UNIT (SSU).