It depends on the reasons for the burnout.
Is it solely the job? Are you trained and experienced enough to do the job properly? If not, given that the company recruited you into the role they should provide you with what you need to reach the required performance level.
Or is it solely the job, but for other reasons, for example, do you have a supportive manager, is your team fully staffed, are you being bullied? Again, the company have a duty to provide the environment you need to be able to do the job properly. Raise any issues with them.
Or is the burnout caused by other life circumstances? Are you struggling to balance work and childcare, or care for an older parent? Speak to the company to discuss possible adjustments to hours or location.
Or are you struggling to balance work with other health issues? Perhaps you are under your GP’s care with depression or anxiety? Again, speak the company about sick leave, recovery plan, return to work plan. You might benefit from a phased return with reduced hours.
You can’t expect an employer to offer an alternative role without looking at the reasons for the burnout and the reasons for not being able to do the existing role.