their treatment of their existing ethnic minorities will make that fairly difficult. the obvious immigrants for them to take would be refugees from the middle east, but I doubt many of them will want to go to Russia.
The obvious source of immigrants are the CIS countries, that's where 90%+ of the current immigration comes from. Also in the past it had no problem attracting millions of immigrants as long as the currency exchange was favorable: https://en.wikipedia.org/wiki/Immigration_to_Russia
Low skilled labor is never going to be a problem while Russia maintains good relationships with Central Asian dictators. Before pandemic Russia had more than 2 million immigrants from that region, all sending money home — it is a major source of cash for those countries. Russian society is racist, but not to the extent when it will make the life of those immigrants unbearable.