The following is the size data in inches.

We want to convert the data to the one in centimeters and write the result to A2:

=spl("=?1.split@p(""x"").(string(~*2.54,""#.00"")).concat(""x"")+""cm""",A1)

Use the function split to split the string into a sequence by the separator x, the option @p means automatically parsing the data type; convert the data in inches in the sequence to the data in centimeters, and convert the converted data to a string sequence and retain two decimal places; use the function concat to concatenate the string sequence into a string with the separator x, and concatenate the centimeter unit “cm”. 

esProc Desktop and Excel Processing
15.3 Split string - separate by multi-character separator
15.5 Parse and extract numbers