I have created a bunch of solo free to play portal content. TDM, infantry conquest, king of the hill. It's not battle royale, but it's not sweats. You said you wanted to practice. Learning the classes and gadgets and aim training is what he needs most. Soloing against other humans doesn't seem any different than just playing with him... ... not sure the point...
EA is no longer advertising these maps as free to play, so who knows. They decide what they want to pay wall.
Give it a try, if you want. These all have bot fill and you can play them solo if you lock them with a password to prevent people joining.
Hardcore king of the hill "free to play": Z6ZFK
Same thing, but not hardcore: ZAEF4
Hardcore infantry conquest "free to play": ZC34V
Same thing, but not hardcore: ZC2RY
Hardcore team deathmatch "free to play": Z3Q8X
Same thing, but not hardcore: Z91ZJ
TDM, "free to play" where you can turn bots off and switch teams: ZG383
Small conquest, "free to play" where you can turn bots off and switch teams: ZGGTZ