On Twitter, Google’s John Mueller said that bold text on web pages is good for web pages and website visitors:
You'll probably get more out of bolding text for human users / usability in the end. Bots might like, but they're not going to buy anything.— John ☆.o(≧▽≦)o.☆ (@JohnMu) 6. Juli 2017
In other words: bold text can have a minor influence on the rankings of a page. However, you should mainly use bold text to improve the usability of your web pages for your website visitors.
Improve your web pages
There are many more factors that influence the position of your web pages on Google and other search engines. Use the Top 10 Optimizer and the website audit tool in SEOprofiler to check your pages. You can create a free account here: