You can use some scrapping tool/script with guest posting footprint, scrapebox can do the work for that,
Scrape a bunch of websites with your required niche, languages, TLDs, etc...
Then you have to reach out to such website & negotiate to get your post published,
Ofc, you'll have to get he right footprints, proxies and tools,
And the right email, your domain email will usually give you better results, but you'll need to warm it up to hit inbox,
And the right approach/letter and from there you can get adjust based in the CR of these emails,
Another easier option would be checking some guest posting databases or reaching out to sellers as
@INCC mentioned,
You'll encounter more spammy and link farming websites in such case, which you'll have to filter and check manually to get the good ones