Hi and welcome to NamePros.
Google have a few times said that the extension (top level domain, TLD) does not impact search - that is it does not give you an advantage or disadvantage. The following from their blog was from 2015 but Google recently reiterated the same points:
https://webmasters.googleblog.com/2015/07/googles-handling-of-new-top-level.html
By far the most important aspect of search ranking will be the quality and amount of content, and how regularly it is updated, and measures of reputation such as how many reputable sites link back to the site.
It is possible that there are minor influences related to the perception of users - e.g. certain extensions are more and less likely to be clicked on by a user (the research I saw was very old but they found that well known extensions like .com are more likely to be clicked on). These higher conversions may in turn help ranking.
There is also some research that shows that an elegant descriptive link is more likely to be clicked on in social media, and that may give a great word.online some advantage in conversion over Word1Word2Word3.com, for example.
But the key point is that it is mainly the quality of the content that is the over-riding influence.
Bob
PS While the initial price on .online may have attracted you for development purposes, note that in most regions the renewal price is significantly higher, so your long term costs on a developed domain name will be higher, although that is probably insignificant compared to the costs of developing and maintaining the site but just wanted to point it out.