No.

Because for under-construction projects, exact dimensions/costs will greatly restrict and cause headache for the developer (and indirectly to you) due to constant changes in raw materials, technology innovation, labour costs etc.

example: wall thickness, if something in future tech allows to make a thinner, cheaper, but structurally stronger and more resilient wall, if agreement enforces wall thickness it's detrimental to both you and the developer to use older tech/materials to stick to SPA defined thickness.

example: maintenance fees/sinking funds, if government suddenly abruptly increased minimum wages, the cost of labour for cleaning and maintenance will go up and cause changes in sinking/maintenance fees. If they're enforced too early this will cause problems in actually hiring contractors/staff fora maintaining the property.

If one is buying from developer, the SnP terms cannot be changed as it is the standard agreement as prescribed in the HDA.

If one is buying subsale, seller cannot guarantee technical specs as he is not the developer. Maintenance and SF is between new owner and JMB and not with seller anymore.

Subsale is sold as it basis including completed developer units

Is similar to buyer asking the used car seller to guarantee the car parts are all original.