My baby is 4 months old and can roll back to tummy, but only sometimes able to roll tummy to back. When I put her to sleep she immediately rolls to her side. she now wants to sleep on her tummy and will adjust to that position at some point in the night. Do I need to be rolling her to her back (she tends to fight me if I do and just go back)? Is it unsafe for her to be on her side or tummy?

Red Nose recommendations are to “always place baby on back for sleep” not baby must always sleep on their back.
https://rednose.org.au/article/red-nose-safe-sleeping-recommendations

Most babies will be getting close to rolling by about 3 months. Eg wriggling/moving around the bassinet.
Most babies will be rolling over by 4- 5 months. Some earlier, some later.
This is very normal as babies grow & become stronger.
Many babies then prefer to sleep on their side or tummy.
This is not something that needs to be stopped. It is important to make the “new” environment as safe as possible.
https://rednose.org.au/article/what-do-we-do-now-that-a-baby-has-started-to-roll-over

Have you now ceased swaddling/wrapping & moved her to her cot?
Babies need arms free & the space of a cot to roll well & safely.
Ensure mattress is firm & flat & nothing soft or loose in her cot.
Continue to always place your baby on back for sleep.

How does she go with tummy time when awake?
Increasing tummy time when awake is important to build upper body strength to roll well (both ways)