Scholarships vary in value (many are low cash value or purely titular) but they are an honour and may carry other benefits (kudos, enrichment activities, free music lessons)
But theynalso carry obligations - musicians expected to be in bands, ensembles and productions, athletes to attend training and fixtures, artists to paint the sets for plays and actors to be in the plays. Academic scholars will be expected to perform well and be very diligent (and join relevant school clubs). They are not means tested.
If you are after a larger reduction in fees, then you need to look at bursaries (which in richer schools can be very generous, and are means tested)
Be aware that a few schools use the terms interchangeably, so do check what they are on about.
In terms of effort, yes candidates will have to audition, be assessed, provide a portfolio, provide sports club references for specialist scholarships. For academics, some have a separate exam for a scholarship, but many just seleclect from the top performers in the regular entrance exam (plus extra interview)