You can get category collection by category id by below code snippet,
<?php
namespace Rbj\Category\Block;
class Category extends \Magento\Framework\View\Element\Template
{
    public function __construct(
        \Magento\Framework\View\Element\Template\Context $context,
        \Magento\Catalog\Api\CategoryRepositoryInterface $categoryRepository,
        array $data = []
    ) {
        $this->categoryRepository = $categoryRepository;
        parent::__construct($context, $data);
    }
    /* $categoryId as category id */
    public function getCategoryById($categoryId){
        try {
            return $category = $this->categoryRepository->get($categoryId);
        } catch (\Magento\Framework\Exception\NoSuchEntityException $e) {
            return ['response' => 'Category Not Found'];
        }
    }
}
Call From template file, Pass argument as Category id,
$categoryId = 5; // category id $getCategory = $block->getCategoryById($categoryId); echo $getCategory->getName();echo "<br>"; echo $getCategory->getUrlKey();echo "<br>"; echo $getCategory->getIsActive();echo "<br>"; echo "<pre>";print_r($getCategory->getData());
