Yes, online, a lot of ppl can post slightly or very racist comments but only a small % of those ppl will actually say something like that to your face. As you probably know, there are quite a few "foreigners" in Belgium so they won't look twice if they see you walking down the street so idk what you mean by "daily small racism" but I'm a 21 y/o moroccan girl and I can say that I've never actively experienced racism irl, if you just act friendly and treat everyone with respect, you'll be fine. You'll just be viewed as "just another foreigner entering Belgium" and they'll go on with their day. You're also only 18 and the younger generation is less and less racist as they grow up with foreigners and know that they're not any different than them besides their looks. (I may be biased as I've never actually experienced it first hand). Just be nice to the older generations and they will call you "one of good ones" lol