If you are website is already indexed in google and wondering how long does google take to reindex your modified or optimized version of your website pages. Google often index instantly once your page is modified and updated your page with more useful information. Once you optimize your page go ahead and submit your website url using url inspection tool and request indexing if you have made changes to your page.
To get your website reindex or index you need to make sure that google is able to crawl your website or not. Once google bot crawls your website it takes some time to get index or reindex in google SERP.
If you have made changes and looking for your website page not appearing on google, in recent times google is having plenty of google indexing bug issues and most of the time new and fresh content or updated content is not indexing and having stale search results issues – https://searchengineland.com/google-confirmed-indexing-issues-causing-some-stale-results-335496
Google indexes instantly if you submit url in search console using url inspection tool and sometimes it takes 4 to 5 days and in case of new website it can take 1 week or high or less to index a new website, Google bot needs to craw and index, since your website is new it takes some time. Once your google pages are indexed you can see them in google search with site:yourwebsitedotcom.
In search console submit your website sitemap file in google search console and google will automatically crawl and index your website even though your website is new, but you need to make sure that updated or modified content or the url which you want to index should present in sitemap file and ask google to recrawl your website https://support.google.com/webmasters/answer/6065812?hl=en.
If you have updated your page or made some changes to your website and not seeing page in google search for a particular query, then it is because after modified or updating your new version of your webpage, google analysed the new version of your webpage and ranking them accordingly using google algorithm for different keywords
It takes 4 to 5 days or even it indexes instantly. You have to update your sitemap file as well once you make changes or page is modified on your website and make it easy for google bot to crawl instantly as soon as you update your page. If you have updated your page and google is not crawling your webpage and google is not showing your updated version of page then use url inspection tool and make sure that your sitemap is updated as well.
In some scenarios, if your website is not updating with the latest version of your webpage, then make sure that you are not blocking google bot to crawl and submit your sitemap once again in google search console and also cross check with live test version of url inspection tool and see the changes you made are reflecting in live url inspection results.
If google is not indexing or reindex your website, then possible reasons is google is still seeing your older version of the page. You need to clear cache version of the page from your website and submit url to reindex making a new request in search console.
If this is the case, its recommended to check with your server logs and http satus codes here, check in browser and url inspection tool that updated or modified page is returning 200 ok response code. Some times due to misconfiguration of server settings, you may see 200 ok response code in browser and when google bot comes and crawls it may see 500 internal server error. So, check server logs and fix if you are getting 500 errors.