International transfer question

I have relatives in the EU, and in the past I’ve sent them money using Western Union and Wise for birthdays and holidays. The costs are pretty high, so I end up bringing cash when I travel. I’m also living there part time, and want to make larger purchases.

Are there any rules or gotchas for sending larger amounts of BTC (eg ($20K+) or just using it as a transfer to withdraw in local currency? I would use it as transfer only, no taxable gains. And if you live in the EU, how would you withdraw those amounts?

Or, is there a better way? I’m looking for least cost, effective and legal transfer of money between the US and EU.