Hi, I bought the Delta theme, I already translated it into my language (RTL), but the site configuration hasn't changed and the LTR remains the same. Do I need to do something else, maybe press some button? (the site is on the local computer).

When RTL language is activated, it automatically switch to rtl.
You can hardcode this by updating delta_is_rtl function

How and in which file to do it?

@Newbie
You should follow first part - add RTL language and use this language. If you are trying to somehow mask English with your translations, that is very wrong way.

Not at all, I did not try to hide the English language, but when I put the file of my (RTL) language into the languages, when I translated it, everything was translated, but the theme configuration, that is, the direction, remained the same as in the LTR language. But there really is no mention of English, only my language, but without a flag and in English for some reason.
Did you mention the delta_is_rtl function where should I insert it?

?

Have you set this language as RTL in lang settings? You might use language codes not recognized by theme.
Rtl function is in theme functions.php, most probably delta_is_rtl()

"Have you set this language as RTL in lang settings?" If you mean General->Language->management Language->RTL language (direction), so yes that what I did, it's not my first Theme before it I translated Alfa theme (and before it a lot of things) , but desided that Delta theme it's beter for this project.
Those my steps: first  I installed the Delta theme , translated it in POEDITE the .po file, created he_HE file with .po. and .mo files, I inserted it in fille of languages where was and still exist en_US file..
There is a code in the picture and I wanted to know where in this code I need to change something so that everything works out?
I also discovered something in the code that seemed to me to be a mistake, I marked it in red.

You have that function printed, set it always to true.

Ok it's works. Thanks.

Cool 

Yes, but you know the flag no appeared, can I manually inserted it somehow?

Country flag? If you used custom code you must upload your image to location where it is missing

I use osclass 8.0.2 and Delta theme I tried to find where I can to upload the flag and did not find the place. I need to do it in admin panel or in the same code of Delta theme?

@Newbie
Sample path:
https://delta.mb-themes.com/oc-content/themes/delta/images/country_flags/large/us.png