* In increasing the block size limit and enhance transaction strength using SegWit aids in solving scalability .
When you perfect the use of blockspace SegWit reduces Bitcoin fees and the general transaction speed and the network can makes series of transaction without increasing it's growth of network,it also helps in transaction signature and transaction data separation that is allowing the creation of more space within each block.
SegWit lmproves security and the state of being trusted of Blockchain technology and increase the strength of transaction .
*. Lightning Network gives the liberty to make off-chain transaction quick and low cost, bringing congestion very low and making scalability high.
Also using Bitcoin side chain can make a way to improve scalability making transfer of asset within various chains, it also make better transaction verification .
These band-aid solutions obviously do not address the root problem; a short look at Bitcoin's mempool today shows that a basic transaction costs $11 for next-block confirmation. And the backlog will only get worse as the difficulty increases in a couple days. We're currently sitting on roughly 1GB of unconfirmed transactions.
Source: mempool.space