Google doesn't take anymore the exact and fixed title/metatitle and meta description to build the SERP. To build the title tag of the SERP, Google normally mix the meta title with relevant H1 and H2 in the page, the site name, etc, plus Google builds the SERP title tag dynamically based on the words searched by users. This also relates to how much the meta title you specified is pertinent to the page contents and to the query of the user searching your page. Meta title and meta description are still the most important part of your website to instruct search engines about how to build the SERP snippet, but they are not the only actors, everything is up to Google.

There are specific reasons why Google rewrites the SERP title and descriptions even if often Google does not a great job, at this link Google’s John Mueller explains during an interview how Google works: https://www.searchenginejournal.com/why-google-rewrites-meta-descriptions/370452
Moreover a great video by the Google team to get some more explanations is available at this link: https://www.youtube.com/watch?v=L3HX_8BAhB4


So as a rule of thumb to ensure that Google will follow as much as possible the meta informations specified in your pages, write meta title and meta description that are strictly related to the contents of the page and respect the length stated by Google, without exceeding the max characters number.

If you enter the page link in the Google search field you won't get the exact meta title and meta description that you specified for that page, the same happens if you search your page based on different keywords, Google will show you different title and description in the SERP that could include only part of meta title and meta description that you specified. Definitely there is not total control over this and how Google builds its SERPs.

More interesting informations about how to write good meta tags for a correct interpretation by search engines can be found here:
http://www.hobo-web.co.uk/definitive-guide-to-using-important-meta-tags