horizon has a setting and glanceclient CLI has a page-size option:
glance CLI:
https://github.com/openstack/python-glanceclient/blob/master/glanceclient/v1/shell.py#L56
@utils.arg('--page-size', metavar='<SIZE>', default=None, type=int,
help='Number of images to request in each paginated request.')
horizon:
https://github.com/openstack/horizon/blob/8e223c950ed69e80034fc8ef7d0861ecd8aeb07d/openstack_dashboard/api/glance.py#L66-L69
def image_list_detailed(request, marker=None, sort_dir='desc',
sort_key='created_at', filters=None, paginate=False):
limit = getattr(settings, 'API_RESULT_LIMIT', 1000)
page_size = utils.get_page_size(request)