For that you can write code similar to this
    field_one = fields.Selection([('option1', 'Option 1'), ('option2', 'Option 2')], string='Field One')
    field_two = fields.Selection([], string='Field Two', compute='_compute_field_two', store=True, depends='field_one')
 
    @api.depends('field_one')
    def _compute_field_two(self):
        if self.field_one == 'option1':
            self.field_two = [('option3', 'Option 3'), ('option4', 'Option 4')]
        else:
            self.field_two = [('option5', 'Option 5'), ('option6', 'Option 6')]