QGIS Print Layout Grid Reference Numeric Format

Using QGIS3.14
The default style of grid labels is single size digits, e.g. 251000E and 5897000N.
I wish to show the grid labels in a format similar to Ordnance Survey with the 51 of the easting and the 97 of the northing in a larger size.
Can this be done within the Print Layout Grid properties or is there a plugin to achieve this?