from the IGCSE chem 2017 spec:
experimental skills are assessed through written examinations.
importance of the experiments includes
- developing experimental and investigative skills based on correct and safe laboratory techniques
- analysing, interpreting and evaluating data and experimental methods
- drawing conclusions that are consistent with evidence from experimental activities and suggesting possible improvements and further investigations
- recognising the importance of accurate experimental work and reporting scientific methods in chemistry
it does help to do the practicals, but you can get to know the method, result and importance of each practical in depth if you study the method well, understand what each one helps prove, and have an awareness of where each one could go wrong (in terms of both inaccuracy and harm).
other skills include
• applying scientific knowledge and understanding in questions with a practical context
• making observations and measurements with appropriate precision, record these methodically and present them in appropriate ways
• identifying independent, dependent and control variables
this means that it's also good to know small details such as how precise each piece of equipment is, as well as being able to comment on features of experiments shown in unfamiliar situations.
it also wouldn't hurt to know the terms associated with scientific experiments, results and accuracy.
in summary, it's possible to know the practicals well without actually carrying them out, though it may take quite a bit of work.