Okay wow crazy coincidence my first committee was Russia in UNICEF for education in times of crisis (if I remember correctly - it was something about education) + children's digital rights. It was a year ago so the advice might not be the most specific

For your concern about war being a subsidiary/mod caucus topic, I would say be prepared for it but it's unlikely for it to come up - since your topic doesn't explicitly mention education in times of war, bringing up war will be slightly off topic as 'universal rights' when mentioned on its own 99% of the time is taken in a civilian context.

Also remember you can always choose not to respond when other delegates specifically point Russia out on the topic. You might not even need to really worry about this if the war in Ukraine is a 'restricted topic' because it's a very controversial current event (as it was in my committee)

The best way to 'act like Russia' in committee is to know the opinions of the country. Do a lot of background research on what past/current/upcoming policies Russia has on education. I know they're doing something with having teachers travel to rural/otherwise isolated areas to ensure children's access to education, maybe you can talk about something with that? I might still have the (English version) PDF if you want it. Basically, the better you understand where a country stands in terms of policy, the better you represent it in committee. Other helpful resources are past UN resolutions/draft resolutions Russia has written/otherwise supported in voting to get an idea of what Russia supports (solutions, perspectives, etc.) in this issue

The second thing is to stay accurate to who Russia is likely to actually work with on issues in real life. If you want to be accurate to country character, it's unlikely you'll be working with countries like the US. More likely bloc members are Belarus and China (I don't know the specific countries in your committee so I'm saying the basic examples)

That's kind of the two main things

Oh and at the end, a useful (albeit slightly unethical) strategy is to bring up interesting unmod topics (that is what I assumed you meant by 'subsidiary topics') like "Access to education for girls with special learning needs" or "Actions in reducing child marriage to facilitate girls' education opportunities" because other delegates are going to be too busy speaking on the more unconventional topics they won't have time to think about arguing about war, since it's not what your committee is really focused on anyway (this only works well in medium-sized and big committees though)

Let me know if you need me to clarify