Thunderbolt 3 raids tend to be a bit expensive but you can daisy chain devices easily with little or no data loss.
TerraMaster TD2 (2bay) TD5 (5bay) get good reviews and impressive read/write speeds with good drives but there not cheap.
OWC ThunderBay 4 mini gets good reviews and not too expensive if you just get enclosure - software based raid - comes with the lite version of OWC raid software.
AKiTiO Thunder3 Quad X )also do a 2 drive enclosure might be worth looking at as well although seem hard to get hold of although mac4us still sells them. https://www.mac4us.nl/product_info.php?cPath=174&products_id=2416&osCsid=6k837qgdo3t5fnpgcorc3s2m96
If you want a DIY option then Highpoint RocketStor 6661A-eSATA (https://highpoint-tech.com/USA_new/series-rs6661a-esata-overview.htm) might be an option - has 4 eSATA connections and thunderbolt 3 - you can easily hook up to SATA drives or they do a Mini SAS version as well. This is just a raid controller and doesn’t have any enclosures but is probably the cheapest way to get a 4 drive raid.
There are some options which come with drives but this gets really expensive. The western Digital G raid but as far as I know you can’t buy it bare and the drives are difficult to change as is the LaCie.